l:!IJ LL Gi>OL. SOC AM. 'IOL. 2. : 8\iO. p;, 2 MAP Of' ROMC ANO CARTRSV/ll THRUST f'AUlTS. !layes' 1891 Map Errata Description of STOP 7, p. 17 The dolostone is along the trend of the calcareous rocks at Alla- toona Dam discussed by Kesler (1950, p. 9). The long part of the cut shows phyllites and metasandstones. The phyllites are prominent to the west, the metasandstones to the east. The metaaandstones contain quartz, potassium feldspar, plagioclase, micaceous minerals, chlorite and a little carbonate. The rocks are intensely sheared. Cross railroad track, follow main paved road east. 101.2 STOP 8 Amphibolite in large L & N Railroad cut to east of Allatoona School. William M. Fairley, University of Notre Dame, Moderator. p. 2, Fig. 4, metasubgraywacke metagraywacke p. 12, line 21, metasubgraywacke = metagraywacke p. 13, Fig. 4, metasubgraywaclce = metagraywacke p. 14, line 9, metasubgraywacke = metagraywacke TABLE OF CONTENTS Page INTRODUCTION -------- Road Log - First Day Stops 1.-8\L-~ ----- ------ - -- - -- -- - 3 _4 Road Log- Second Day Stops 9-15 - - - - - - - - - - - - -- -- - -- -- - - --- - _]9 Stop 1 Carter's Dam - Cartersville Fault ----------------- ------------------ --------------------------------------------------- 7 Stop 2 Georgia Route 53 - Cartersville FaulL.. ------------- ---------------- -----------------------------------------------12 Stop 3 F airmount, Georgia - Cartersville Faull - - -----~---- _ 14 Stop 4 FJexatile Slate Mine - Cartersville Fault -------------- -------- ......................................14 Stop 5 Cass Station, Georgia- Upper Rome Formation -Folds and Faults................................. . ---------------- ...16 Stop 6 Paga # 1 - Barite Mine......... --------------------- .. _____________. .................... --------------------------------- ___________16 Stop 7 L & N Railroad Cut - Schists and Dolostones .......... ........................................---------------------------------17 Stop 8 Allatoona Railroad Cut - Amph.iboJitc....... - -------------------- --- - ---- ----------------17 Stop 9 H. E. Smith Property - Middle Rome Formation - Folds and Faults ....... ------------------ ....................20 Stop 10 Wolfpen Gap Road - Weisner Section........... ............. . -------------------------------------------------- ................21 Stop 1.1 Breccia.................................. ___________.. ._ ................. ................................ ..................... .......................24 Stop 12 Wolfpen Gap Road- Contact with Corbin Gneiss. ------------- - - - - - 24 Stop 13 0)Qper Branch Landing - Corbin Gneiss - Lunch 26 Stop 14 Allatoona Dam - Weisner Formation (?) - - - --------- - - -- -- - -- - - _27 Stop 15 Cooper Branch - Contact with Corbin Gneiss 27 The Cartersville Thrust at Cartersville, Georgia ....................... ------------------------------------------------------ .....................28 by William M. Fairley, University of Notre Dame Comments by A. S. Furcron ------------- -------------- ------------------- ---------------------------------------------------- ...................33 1. B. Hadley - -- - -- - ,_ _ _34 John Rodgers.. -----------------------------------------------------------------3 6 Bibliography - - ----- ---- -- -------- ---- - 37 1 LiST OF ILLUSTR ATIONS Location of Field Trip Stops_____________________ ----------- ______ __ . - - - -- - --- ....... ____________Front Cover Hayes' 1 ~91 Map of Cartersville Region.................. .....- - __ ------------- .. ...... Inside Front Cover Hayes' Map of 1900- - - - - - - - - - Inside Back Cover Fairley's Map (this paper) of correlations northeast of Cartersville area________ _ .Outside Back Cover P age Figure 1-Topographic Map of Carter's Dam Site, showing boring and section locations and fau lt trace after Coogan et al., 1963 -------- 9 Figure 2-Geologic Section after Coogan ct al., 1963 ____ to Figure 3- Geologic Map, showing location of Stops 2. 3, and 4; and isogrud lines in the Fairmount, Georgia, arca ................. ................ ................... ...................... .................11 Figure 4-Negative print of thin-section of graded mctasubgraywacke bed from roadeut along Georgia Route 53, 1-1h mi . east of U.S. Route 411 intersection --- . _ 13 F igure 5-Equal-area diagrams of plots of cleavage poles from slate west of Cartersville Fault and p.lots of lineations from east of the Fattlt in the map area (Figure 3). The diagrams have been divided into areas representative of the percent of cleavage poles or lineations which fall. within one percent of the area of the circle. North is at the top or the circles; so, most of the cleavage p lanes strike NE and dip from 45 SE, and lineations strike NW and are about horizontal. _____13 Figur.e 6-Bcd between Conasauga carb<.mate and slate truncated by Cartersville Fault at Flexatile Mine. Ocoee? Precambrian phyllite has been thrust over Conasauga Cambrian rocks . _ ____15 Figure ?-Photograph of clay after deformation. The lines were originally straight, and the ellipses were circles ( 1-YCartersville "" OATLANTA \ \ "Macon ' ' '"' \ ' \ Figure Topographic mop of Carters Dam Site area showing boring and section locations and fault trace. ' ; z - ~~~9.., '-< GEOLOGIC SECTION A-A (LOOKING SOUTH) SCALE : r''=50' 50' 0 50FT El . 900 Et. eoo ....... 0 OCOEE SERIES (Phyllite with occa sional Quartzite beds in this section) Et. 7oo e: 1. eoo C-8 r_ ' ~',,,9/' I Y h {f"J'< ,' )1 /HI' A :ASV ,~W ,', /"/ //ZH ~ ClJ ::0 Lim e ston e, Do Ioston e, and Slate ):> z 150 0 - 4000 1? OCOEE SERIES? Metagraywacke, Schi st 2500' + -o ::0 fT1 Metosiltstone (") 2000 - 25 00' ):> ~ ClJ ::0 )> Upper Phyllite z 0 - 5 00' M etog roywo c ke, Phyllite 600 - rooo' Lower Phyllite 0- 30 0' Cartersvi ll e Th r u st Faul t Fault Dip Syncl ine Bedding - 21 14 --L 1 One Mil e___J Fig. 3-Geologic Map, showing location of Stops 2, 3, and 4, and isograds in the Fairmount, Georgia, area (Smith, !. W., 1959). 55.5 59.1 59.8 60.2 60.2 61.5 61.9 TURN AROUND. Return to US Route 411. STOP 2 TURN LEFT on US R oute 411 south. NOTE: RETRACE ROUTE TO JUNCTION WITH GEORGIA ROUTE 53 ON NORTH SIDE OF FAIRMOUNT, GEORGIA. TURN LEFT on Georgia Route 53 east (north side of Fairmount). Conasauga shale, on right. STOP 2: Cartersville Fault. James W. Smith, Georgia Geological Survey, (moderator). NOTE: HIGHWAY TRAFFIC TS EXTREMELY DANGEROUS, WAIT FOR FLAGMEN TO ACCOMPANY YOU ACROSS THE ROAD, AND STAY ON THE FAR SIDE OF THE ROAD FROM THE PARKING AREA WHILE GOING UP AND DOWN THE ROAD. The first road-cut uphill (east) from the parking area contains Conasauga shale* which has weathered light greenish gray. Further uphill in the same road-cut is Conasauga dolostone that is light gray and fine- to medium-crystalllne. A few feet above the east end of this road-cut are exposures of a gray, crinklcy phyllite which is probably equivalent to the Precambrian Ocoee Series. Certainly the Ocoee rocks here ar:e not lithologically correlative of any of the rocks of Paleozoic age in the Valley and Ridge Province to the west. The Cartersville Fault would have to be between the Conasauga Group and the Ocoee Series (figure 3). At the third major road-cut there is much gray mctasubgr.aywacke interbedded with dark gray phyllite. Beds dip about 15 degrees east and are rightside up as indicated by graded bedding (figure 4). The Ocoee Series here is about 5,000 feet thick; so, the displacement along the Cartersville Fault is at least this distance. Direction of movement along the fault wos probably largely northwest, for lineations east of the fault and slaty cleavage west of the fault show that the major translation within the rocks was to the northwest (figure 5). These lineations are very prominent and most are positioned northwest. Some lineations are quartz grains deformed so that they are up to 30 times longer than they arc thick. This much elongation is believed to be associated only with the major direction of movement in deformed rocks. TURN AROUND. Return to US Route 411 via Georgia Route 53. TURN LEFT on US Route 411 south in Fairmount, Georgia. NOTE: WE WILL EAT A BOX LUNCH IN THE CITY PARK IN THE CENTER OF THE CfTY AT 12:00 NOON, GEORGIA TIME. TURN LEFT at traffic light in Fairmount, Georgia, on paved road . *Conasauga argillaceous units have slaty cleavage throughout the region north to south and are called slates by JWS. 12 STOP 2 (C ontinued) Fig. 4- Negative print of thin-section of graded metasubgraywacke bed from roadcut along Ga. Route 53, J-1/2 mi. east of U.S. R oute 411 inter- section (Smith, 1957). Actual size. 42 SLATEY CLEAVAGE POLES N 85 LINEATIONS D 0-5~ 7-9 "4 rnm 12-14"4 m 16-19 "4 D ~a UIID ~ - o-2-x. 3 - 7% s-14"4 15-231. 2.4'-34% 3539"4 Fig. 5-Equal-area diagrams of plots of cleavage poles from slate west of Cartersville Fault, and plots of lineations from east of the Fault in the map area (Figure 3). The diagrams have been divided into areas representative of the percent of cleavag.e poles or lineations which fall within one percent of the area of the circle. N orth is at the top of the circles; so most of the cleavage planes strike NE and dip 45 SE, and lineations strike NW and are about horizontal (Smith, 1959). 13 STOPS 3 & 4 60.2 TURN AROUND. Return to US Route 411 via Georgia Route 53. 61.5 TURN LEFT on US Route 41 t south in Fairmount, Georgia. NOTE: WE WiLL EAT A BOX LUNCH lN THE CITY PARK l N THE CENTER OF THE CITY AT 12:00 NOON, GEORGIA TIME. 6 1.9 TURN LEFT at traffic light in Fairmount, Georgia, on paved road. 62.4 STOP 3: Cartersville Fault; Just east of Fairmount, Georgia. James W. Smith, Georgia Geological Survey, (moderator). Walk up dirt road to east; view fault exposed on north side of road. Ocoee Series phyllite and metasubgraywacke have been thrust over Conasauga shale. The Fault is well exposed and dips about 47 east. X-ray diffraction traces show sharper peaks for the micas of the Ocoee Series phyllite than for the Conasauga shale. This indicates that the phyllite has been metamorphosed to a higher degree than the shale; so, there is a metamorphic break across the Fault. Isograds roughly parallel the Fault (figure 3); therefore, this metamorphic break proves a vertical component of movement along the Cartersville Fault since regional metamorphism. A clay zone containing limonite and wad occurs at several places along the Cartersville Fault east of Fairmount. Here, this zone is about l-1/2' thick and contains a light gray, quartz mylonite up to 2" thick. TURN AROUND. Return to US R oute 41 1. 62.9 TURN LEFT on US Route 411 south at traffic light. NOTE: FOLLOW US ROUTE 4 11 SOUTH TO FLEXATILE SLATE MlNE, 3.6 MILES. 66.5 TURN LEFT into Flexatile Slate Mine. 67.0 STOP 4: Flexatile Slate Mine exposure of Cartersville Fault: James W. Smith, Georgia Geological survey, (moderator). Geology: The shale here is similar to the Conasauga shale of the previous two stops, except fresh, greenish gray shale is exposed in the mine. On the east side of the open-pit that is presently being mined, the Cartersville Fault is exposed (figure 6). T he fault plane dips 45 degrees east. The bedding plane between Conasauga shale and Conasauga carbonate rock has been truncated; both rock types are in contact with phyllite that is most likely Precambrian Ocoee Series rocks. The Fault Zone is quite permeable, for when it was penetrated underground in the mine, much water came from the Zone. 14 STOP 4 (Continued) Figure 6--Bedding plane (d.ashed line), between Conasauga carbonate and slate, truncated hy Cartersville Fault (solid ink line) at Plexatite mine. Ocoee(?) Precambrian(?) phyllite has been thrust over Conasauga Cambrian rocks (Smith, 1959). Mining: The quarry was first opened in 1909 and operated until 1911 or 1912, and it was worked from February to June 1913. The Richardson Company built a plant here in 1920 to make split slate roofing shingles. A short time later the slate was ground to make granules for coating roofing paper, and production of split slate was discontinued. Funkhouser Mills bought the operation in 1927 and the ground slate finer than granule size was then utilized as a filler in fertilizer. lt'> use in fertilizer is now banned, but it is used as a filler in the asphaltic coating on roofing paper. In 1959 Funkhouser Mills merged with Ruberoid Company. The operation has been continuous since 1920, except for a month at a time during the Depression. Mining started as an open-pit; then in 1933 underground mining began but was not continuous underground until 1938. The second open pit was started in 1963, and underground mining was discontinued. TURN AROUND and return to US Route 411. 67.5 TURN LEFT on US Route 411 south. NOTE: RETRACE ALONG US ROUTE 411 SOUTH (15 MILES) TO US ROUTE 41 IN CONASAUGA AND ROME FORMATIONS. 15 R2.7 gJ.2 83.3 g5.1 85.5 93.2 94.1 94.2 95.3 TURN RIGHT on US Route 41 north. STOPS 5 & 6 Rome Formation shale and carbonate rocks. Pettit Creek crossing. STOP 5: Cass Station, Georgia, road-cut in Rome Formation, calcareous silt- stone, sandstones, and shales. Robert D. Bentley, Georgia State CoJiege, (moderator). Several folds and faults exposed in cut show characteristic style of deformation in this part of the Valley and Ridge Province near a fault zone. Croft ( 1963) mapped a fault through this cut. Note that the shale units display a slaty cleavage and show slight recrystallization. The local faults follow two trends north goo west and north-south, and show high angle reverse displacement with some lateral components. Ripple marks and crossbedding are found in some of the coarser grained units. The fault zones are filled in places with quartz-carbonate-feldspar (?) (kaolinite) veins. NOTE: CONTINUE ON NORTH ON US ROUTE 41 TO TURN AROUND. TURN AROUND and follow US Route 41 south through Cartersville, Georgia, across the Etowah River to junction with Georgia Route 294 in Rome, Shady and Weisner Formations. TURN RIGHT on Georgia Route 294. TURN RIGHT on Georgia Route 3. TURN LEFT on gravel road leading to Paga No. 1 Mine. NOTE: SHADY DOLOSTONE EXPOSED IN OLD PITS ALONG ROAD LEADING TO PRESENT MINING SITES. STOP 6: Paga No. l Barite Mines. James W. Smith, Georgia Geological Sur- vey, (moderator). At least 50 stratigraphic feet of Shady dolostone are exposed in pinnacles in the Paga No. 1 Barite Mine. The dolostone is largely dark gray and some is light gray, fine-to medium-crystalline, thin to massively bedded, and contains a few phyllitic partings indicating that these rocks have been metamorphosed. Barite and quartz form prominent veinlets in a few of the pinnacles. Kesler (1950) mapped this dolostone as Rome Formation; however, Croft (1963) mapped it as Shady dolostone. John Rodgers (personal communication, 1966) feels that Kesler confused the stratigraphy and mapped Shady as Rome, and Rome as Conasauga. 16 STOP 7 Mining: The Paga No. 1 Barite Mine has been operated almost continuously since 1916; and this is the largest open-pit in the Cartersville area. ThompsenWeinman Company is the present owner. The minable barite occurs in the clay residuum from dolostone. The residuum is up to 150' thick, and the average content of barite is about 15 per cent by weight. TURN AROUND and retrace route to Georgia Route 3. 96.4 TURN RIGHT on Georgia Route 3. Continue east on Georgia Route 3 until just east of US Route 4 1 (underpass) in Shady and Weisner Formations. 98.4 BEAR LEFT on paved road (to Allatoona) just pass underpass (US Route 41). 98.5 Mosteller brothers' iron ore mine in Weisner Formation, on left. 99.2 Cartersville Fault (?) in valley, Shady Formation (west) against Ocoee Series (?) or Talladega Se-ries (?) (east), according to Croft ( 1963 ), Hayes ( 1901), and LaForge (1919). 99.8 STOP 7: Large L&N railroad-cut in phyllite and schists and dolostonc.'l. Wil- liam M. Fairley, University of Notre Dame, (moderator). Interbedded ampbibolites and quartz-albite layers occur here. The high quartz content of the quartz-albite layers suggest that they are of sedimentary origin, but it is difficult to conceive of a source rock(s) which would simultaneously supply so much quartz and albite with so few other constituents. (See the modal analyses, Table 1). The amphibolites are of even more uncertain origin. Kesler (1950) considered them to be para-amphibolites; Croft (1963) said they are ortho-amphibolites. This outcrop is the northwestern-most of several bands of amphibolites. Those to the southwest were considered by Hurst ( 1952, p. 41) to be para-amphibolites, but he has suggested an igneous origin for the (probable) equivalent of this body where it crops out on U.S. Route 4 I just to the southwest (Hurst, 1955a). The following interpretation is offered for the purpose of discussion. The amphibolites in this cut lie high in the Murphy syncline, perhaps in the Andrews Formation. To the northeast similar amphibolites lie in the Andrews Formation which Fairley (unpublished) bas traced from the Tate quadrangle, although the intervening area has not been completely mapped. They formed during a time of early Paleozoic volcanism which terminated the quiet conditions under which the Murphy Marble was deposited and re-established a regimen of clastic deposition (the Andrews Formation). Volcanic and sedimentary components are intermixed in variable proportions, perhaps in a manner similar to that suggested by Clarke (1964, p. 20) for amphibolites in Alabama. Possibly this amphibolite is roughly equivalent to the Marble Hill hornblende schist which may contain volcanic components even though its variable quartz and carbonate contents indicate a sedi- mentary origin. To be real speculative, we can even suggest that the metagabbro at Marble Hill in the Tate quadrangle lies in the neck of one of the volcanoes which produced the materials for the amphibolites. The relatively unmctamorphosed state of the gabbro, however, suggests that it was intruded after the first regional deformation. 17 Hornblende Epidote, etc.* Plagioclase** Quartz Chlorite & Biotite Sphene Opaque Carbonate Table 1: Modal Analyses of Amphibolites and Associated Rocks. 1 2 3 4 5 6 7 8 1 73 67 43 73 70 55 3 5 2 tr 17 13 21 49 17 22 39 20 7 12 16 37 3 7 43 10 3 2 3 8 17 20 tr 1 tr 1 1 1 1 2 1 tr 1 tr tr 1 2 1 6 2 4 STOP 7 (Continued) 9 10 11 3 5 64 2 17 47 46 11 44 36 6 5 11 tr l tr 1 tr *Clioozoisite and zoisite are included with epidote. Note the relationship between this mineral group and plagioclase in the amphibolites. **Most, if not all, the plagioclase is albite. Very small grains are untwiimed and difficult to distinguish from quartz so that the stated percentages are only approximate. Number 5 is probably from a shear zone. NOTE: TURN AROUND AND RETRACE ROUTE TO US ROUTE 41. 105.7 Go under overpass, TURN LEFT on US Route 41 south. 118.1 End of lst Days' Log. 18 ROAD LOG - SECOND DAY STOPS 9-15 0.0 1.3 1.9 6.7-6.8 8.9 9.6 10.6 11.3-11.5 11.6 11.7 12.4 12.5 13.6 14.4 15.0 16.0 Assemble 8:00 AM Smith Motel, Kennesaw, Georgia, 5 miles north of Marietta, Georgia, on west side of Route 41. Smith Motel, TURN LEFT ON US Route 41, north. NOTE: NEXT ll MILES IN CRYSTALLINE ROCKS OF PRECAMBRIAN (?) OR PALEOZOIC(?) AGE ALONG US 41 NORTH. Amphibolite, on right. Weathered schists, steeply dipping to southeast. Exposure of granite at Allatoona Creek crossing arm of Allatoona Lake. Cobb-Bartow County line; amphibolite, dipping 45 southeast. Amphibolite with foliation dipping 20-40 southeast may be traced to railroad cut to north (Stop 8). Carbonaceous phyllite, dipping southeast, on left. Cartersville Fault (?) in valley (location according to Croft, I963); definite Palcozoic sequence to west. NOTE: NEXT 9 MILES IN CAMBRIAN SHADY AND WEISNER FORMATIONS, DEEPLY WEATHERED, ALONG US ROUTE 41 NORTH. Pumpkinvine Creek crossing. Shady Formation, deeply weathered, on left. L & N Railroad overpass. Weisner Formation, on right. Shady Formation, on right. Red Top Mtn. State Park junction, on right. Allatoona reservoir road, on right. Thompson-Weinman plant, on right. 19 16.5 16.7- 17.1 17.6 17.8 20.3 22.3 24.4 27.1 27.7 31.5 31.7 31.9 32.0 33.6 33.7 33.8 34.0 34.1 35.0 35.3 Shady Formation, old barite pit, on right. STOP 9 Shady Formation. 1st traffic light in Cartersville, Georgia. Ranch House, on right; town of Cartersville, Georgia, on left; barite mining in distance, on right. TURN RIGHT on US Route 411 north, Shady Formation on left. NOTE: NEXT 12 MILES IN ROME (?) AND CONASAUGA FORMATIONS OF CAMBRIAN AGE ALONG US ROUTE 411 NORTH. Gray shale in Rome Formation, on right. Exposure of shales of Rome Formation (?). Center of White, Georgia. Conasauga limestone. Rydal, Georgia, Post Office, on right. Conasauga limestone. TURN RIGHT on Georgia Route '140. Conasauga Group limestone, on left. Folds in Rome Formation(?) shales. Crossroads. Oak Hill Church, on left. Rome Formation (?) shales and carbonate highly deformed. TURN RIGHT on narrow gravel road. BEAR RTGHT on gravel road . STOP 9: H. E. Smith "Bull" Pasture. Robert D. Bentley, Georgia State College and William M. Fairley, University of Notre Dame, (modr.:rators). This stop is in 20 STOP 10 an approximate position of the projection of the Fault along the base of Johnson Mountain above the Flexatile Mine to the north. Croft (1963) mapped the exposures in H . E . Smith's "Bull" pasture as his middle unit in the Rome F ormation. The rocks to the west are Rome shales and to the east are Shady dolostones. The rocks on the west side of the pasture arc calcareous phyllites which show evidence of two periods of deformation. Numerous small folds are found in the phyllitic units. NOTE: CONTINUE ON MATN GRAVEL ROAD ACROSS SUGAR HILL CREEK BE ARING LEFT AT 1st CR OSSROADS. 37.4 TURN LEFT on US R oute 411 south. 40.5 Center of White, Georgia. 40.7 T URN LE FT on Wolfpen Gap-Miller's Chapel R oad. 40.8 Ncar fault (Croft, 1963) between Rome Formation (west) and his upper unit of Shady Formation (east) . 41.4 Fanlt (Croft, 1963) between upper unit of Shady Formation (west) and upper unit of Weisner Formation (east). STOP 10: Section of Weisner Formation (upper?) along Wolfpen Gap R oad. R obert D . Bentley, Georgia State College; W. Robert Power, Georgia Marble Company, (moderators). Unit#: 1 Thickness: 45 ft. 2 2 ft. 3 1 ft. 10 in. 4 7 ft. 5 1 ft. 6 7 ft. 7 1 ft. 9 in . 8 2 ft. 8 in. T he followi ng is a measured section (Richard D. Davis, Georgia State College) starting at fault on west to breccia zone on east along Wolfpen Gap Road. Croft (1963) mapped a continuation of the fault (Stop 5) between upper unit of Shady F ormation (west) and Weisner Formation (east). D escription R ed and gray, weathered phyllites; local gouge zone. F ault zone. M assive, gray metaquartzite with manganese oxide staining. Yellow-gray scricitic phyllite. Quartz-ite. Phyllite with mylonites. Mctaquartzite; strike and dip: N 30 E, 76 SE . Phyllite. M etaqua rtzite. 21 Unit#: 9 Thickness: 10 in. 10 18 ft. 11 3 ft. Ph in. 12 11 in. 13 8 in. 14 1 ft. 9 in. 15 5 ft. 3 in. 16 8 ft. 8 in. 17 4 ft. 18 24 ft. 19 119 ft. 20 2 ft. 21 2 ft. 8 in. 22 39 ft. 23 26 ft. 24 32 ft. 25 3 ft. 26 12 ft. 27 9 ft. 28 231 ft. 29 3 ft. 6 in. 30 29 ft. 31 46 ft. 32 6 ft. 6 in. 33 4 ft. 6 in. Description Red and brown phyJlite, sheared. STOP 10 (Continued) Metaquartzite. Buff weathered, gray, fresh phyllite. Metaquartzite. Gray-green on fresh surface; sheared phyllite. Metaquartzite. Deeply weathered phyllite with same metaquartzite beds. Metaquartzite with fracture cleavage; manganese oxide along cleavage planes. Yellow-brown weathered phyUite, gray-green where fresh. Drecciated zone, metaquartzite .fragments with manganese oxide matrix. Covered interval. Metaconglomerate-quartz pebbles 1h" - ~" diameter. Phyllite, gray-green on fresh surface. Metaquartzite, strike and dip: N-S, 22 E. Covered interval. Metaquartzite, yellow-brown limonite stain, deeply weathered, strike and dip: N 46 W, 21 o SE. Fault zone; phyllite with some metaquartzite; secondary iron staining. Buff colored phyllite, gray with lavender banding on fresh surface; extremely :;heared and fractured; overlying units related by fault zone. Alternating metaquartzites and phy1lites, yellow-brown and red iron staining, 6" lens of manganese oxide near center of unit, strike and dip: N 31 E, 26 SE. Covered interval. Alternating metaquartzites and phyllites, manganese oxide staining. Gray and red scr icitic phyllite, some metaquartzite, strike and dip: N 10 E, 38 SE. Red-gray phyllitic metaquartzite, deeply weathered. Metaquartzite. Phyllite. 22 Unit# : Thickness: 34 3 ft. 8 in. Description Phyllitic metaquartzite, deeply weathered. STOP 10 (Continued) 35 33 ft. Phyllite. 36 4 ft. 8 in. Phyllite, reddish color and some metaquartzite. 37 30 ft. Massive, light blue-gray metaquartzite with sulfide veins (pyrite? ) lJ8" to 2" "SULFIDE STRIKE" thick, manganese oxide staining, strike and dip: N 28 E, 46 SE. 38 72 ft. Phyllite. 39 21 ft. Metaquartzite. 40 378 ft. Covered interval. 41 17 ft. Gray sericitic phyllite with some metaquartzite. 42 16 ft. Alternating phyllites and metaquartzites, deeply weathered, strike and dip: N 26 E, 48 SE. 43 1 ft. Shear zone. 44 42 ft. Alternating metaquartzites and phyllites. 45 76 ft. Dark gray sericitic phyllite; deeply weathered. 46 228 ft. 47 137 ft. Covered interval. Extremely fractured and weathered quartzitic phyllite, lower 20' - 40' of unit grades into fault zone. 48 48 ft. 49 8 ft. 50 12 ft. 51 67 ft. 52 756 ft. 53 407 ft. 54 298 ft. Metaquartzite, vertical bedding. Sericitic phyllite and metaquartzites, vertical bedding. Metaquartzite, grading into fault zone of highly brecciated metaquartzites and phyllites. Fault zone, brecciate. Mostly covered. Saprolite, red-brown color. Fault (?) breccia, metaquartzite and phyllite fragments, zones of specular hematite. 3355 ft. Total Thickness (assuming no structural complications.) 23 41.7 42.0-42.4 42.7-42.8 42.8 42.95 43.0 Sulfide veins in massive metaquartzite (Unit 37). STOPS 11 & 12 NOTE: CONTINUE ON EAST ON WOLFPEN GAP ROAD. STOP 11: Brecciated Weisner Formation. Robert D. Bentley, Georgia State College and W. Robert Power, Georgia Marble Company, (moderators). Exposed on the north side of the road is approximately 300 feet of breccia of unknown origin. Thjs stop is in line with the location of the Cartersville Fault as shown by Hayes ( 1900) and the State Geologic map of Georgia (1939). Problem: Is this the Fault? Slickensided fragments of metaquartzite and specular hematite can be found Locally along the cut. Some suggestion of stratigraphic units (quartzite, phyllite, etc.) can be seen on a gross scale. AIL units dip at moderate angles to the southeast. This zone appears to be typical of the crushed breccia zones mapped by Kesler ( 1950). Sheared gray phyllite (Wilhite of Hayes) middle unit of Weisner Formation (Croft 1963), intensely sheared. Sheared metaquartzite on right. TURN RIGHT on narrow gravel road. STOP 12: Contact of Corbin gneiss on right in road gutter. Robert D. Bentley, Georgia State College and W. Robert Power, Georgia Marble Company, (moderators). The purpose of this stop is to show the contact relations of the Weisner lithology with the Corbjn gneiss. Here the contact can be located within a few feet in the saprolite in the road gutter on the east side of the road. The contact exposes to the northwest highly sheared quartzites of the Weisner (?) Formation and to the south coarse-grained Corbin gneiss. The contact zone is trending N 30 to 40 E, dipping 45 to 50 SE. Extreme crushing of all units west of the gneiss is apparent. Small 3"- 10" quartz zeins (?) of blue quartz show extreme cataclastic texture. The fine-grained phase of the immediate contact displays many small rounded and stretched grains of blue quartz in a ground mass of finer ground up quartz and muscovite. This zone is 4-8' thick and grades laterally into the sheared quartzite with scattered phyllitic layers of Weisner (?) Formation to the north. The Weisner (?) rocks are dipping uniformly 40-60 SE with intensely cataclastic textures. Scattered phyllitic layers are found from the contact, to the junction with the improved Wolfpen Gap road to the north. TURN RIGHT, south, on narrow gravel road. NOTE: THE ROUTE LEADING TO NEXT STOP FOLLOWS THE APPROXIMATE CONTACT FOR 5 MILES. 24 43.65 43.9 44.2 45.2 45.3 45.9 47.0 47.1 47.5 47.55 48.1 48.5 48.8 49.05 49.15 49.25 49.3 49.5 49.75 49.95 50.00 Contact of Corbin gneiss with Weisner Formation (?). STOPS 11 & 12 (Continued) Weisner metaquartzites. Corbin gneiss, on right. Corbin gneiss boulders. Corbin gneiss boulders (USBM 1065-1 ? ). TURN LEFT (sharp) on gravel road. Cross Georgia Route 20. BE CAREFUL! Rowlaud Springs Church, on left. BEAR RIGHT on paved road-Double Springs, Georgia. TURN SHARP LEFf on Georgia Route 294. Boulder of Corbin gneiss, on right. Contact (?) of Corbin gneiss with Weisner Formation (?). Weisner phyllite unit showing multiple deformation. Weisner (?) metaquartzite and conglomerate. Sheared Corbin gneiss in road-cut, to right. McKaskey Creek Road junction. Contact of Corbin gneiss (sheared and weathered) with basal (?) conglomerate. Contact of Corbin gneiss and basal (?) conglomerate, on right (This is location of Stop 15.). Picnic Area #2 road. TURN LEFT on road to Cooper Branch Public Launching Ramp and Picnic Area #1. Contact with Corbin gneiss and Weisner (?) Formation. 25 50.1 TURN LEFT into Picnic Area # 1. STOP 13 50.2 STOP l 3: Cooper Branch Landing, Corbin gneiss. Benjamin A. Morgan, Geor- gia State College, (moderator). Excellent outcrops of Corbin gneis:s are exposes in the area of Cooper Branch Landing, about ~ mile north of the Allatoona Dam. A series of low rounded outcrops are particularly abundant near the lake shore, and fresh samples are easily obtained from both outcrops "in place" and from boulders and cobbles lying on the shore. The outcrops continue in the smaJJ islands in the lake immediately east of the boat landing. The Corbin gneiss is a coarse-grained, sheared rock with exceptionally large porphyroclasts of white microline, coarse-grained, blue quartz, and a fine grained, highly sheared matrix. consisting of these minerals as well as biotite, muscovite, garnet, and others. Banding in the rocks, defined by stringers and segregations of blue quartz, is usually either weakly present or entirely absent. An accurate modal analysis of a ve.ty coarse-grained rock with a non-homogeneous texture such as the Corbin gneiss is difficult to obtain. Several large blocks of Corbin gneiss were cut and macropoint count was made of microcline porphyroclasts and blue quartz utilizing several square feet of cut material. Mineral abundances of the matrix were obtained from examination of powders and several thin-sections. The following modal analysis was thus obtained: quartz 41 microcline 36 biotite 10 m u scovite 4 garnet 4 chlorite, opaque minerals, rutile, epidote, zircon 5 Quartz grains have a remarkably consistent and pronounced blue color. The coloration is attributed to the large number of very fine rutile particles incorporated in the grains; rutile can be identified only with a l OOOX magnification using an oil immersion lens. Microclinc grains arc very large, often greater than 10 centimeters in length. Crushing and shearing of these grains is especially evident in thin sections which show bent or totaUy disrupted microcline grid twins and carlsbad twin sections; the crystals are characterized by extreme undulatory extinction. The large microcline crystals are considered as porphyeroclasts in view of their highly sheared character. Exsolution lamallae are not common and perthitic textures characterize only a few of the grains. A preliminary check of the composition of the microcline was made by measuring the (201) reflection angle using a Phillips Norelco X -ray diffractometer and copper radiation following the method of Tuttle and Bowen (1958). The plagioclase content of microcline was estimated to be about 20%; accurate determination would require the complete removal of quartz and thermal homogenization of the sample. 26 STOPS 14 & 15 Biotite is present in subordinate amounts. Jn thin section biotite has deep brown to yellow pleochorism; inclusions of rutile, apatite, and opaque minerals are common. Garnet is never abundant and usually it is partly replaced by chlorite and epidote. No definite evidence for the origin of the Corbin gneiss can be given here. Jt should be pointed out, however, that the modal analysis of this unit indicates a bulk chemical composition rather far removed from the thermal minimum composition which Tuttle and Bowen studied. Rounded zircons arc common and may have once been detrital grains. Fine-grained schists are interbedded with the Corbin gneiss in many areas including a highly weathered zone in the Cooper Branch Landing area. These zones could be interpreted as relcct sedimentary bedding. Whether sedimentary or igneous in origin, the Corbin gneiss probably has had two or more periods of deformation which were accompanied by metamorphic changes in mineralogy and possibly bulk composition. LUNCH STOP NOTE: TURN AROUND AND RETURN TO GEORGIA HIGHWAY 294. 50.5 TURN LEFr on Georgia Highway 294. 50.9 STOP 14: Allatoona Dam : Weisner (?) Formation. Robert D. Bentley, Georgia State College and W. Robert Power, Georgia Marble Company, (moderators). NOTE: TURN AROUND, FOLLOW GEORGIA 294. 51.7 STOP 15: Contact of Corbin gneiss and metasediments. Robert D. Bentley, Georgia State College, and W. Robert Power, Georgia Marble Company, (mod- erators). The following quote from Hayes (1901, p. 406) describes this stop: "This area of Corbin granite at one time probably formed an island, since it is surrounded, in part at )east, by rocks derived from its waste. These are feldspathic conglom- erates, in which the blue quartz and the porphyritic crystals of microcline, which characterize the granite, can be readily distinguished. In some places the transition from granite to conglomerate is so gradual that it is difficult to determine the exact boundary between the two formations. The development of the gneissoid structure in the granite evidently took place after it was deeply buried by sediments; for the alteration of the latter is even more marked than that of the granite itself. Whenever the granite is not bordered by coarse conglomerate or quartzite, it is in contact with black graphitic slates, which generally overlie the coarser sediments." 53.7 TURN LEFT at Sinclair station in Double Springs, Georgia. 54.3 Approximate contact with Corbin gneiss. 54.4 Highly contorted phyllites. 56.8 US Route 41 just north of Cartersville, Georgia. End of Field Trip. 27 THE CARTERSVILLE THRUST AT CART.ERSVILLE, GEORGIA by William M. Fairley Introduction. Correlations parallel to strike arc relatively easy to make in the crystalline rocks of the Appalachians. Correlations perpendicular to strike are difficult to make. Of great interest are the correlations proposed across the strike which relate the rocks of the Valley and Ridge Province with those of the Blue Ridge and Piedmont Provinces. Kesler (J 950) made such correlations in the Cartersville district but generally they have not been accepted (Croft, 1963). The purpose of this discussion is to suggest that some of Kesler's correlations may be right, and any blanket denials of his conclusions are, in the present state of our knowledge, unwarranted. The reader should have the following maps of the Cartersville area at his disposal: Hayes (1900, p. 405) (See inside back cover. )-this map also appears in Watson ( 1904); Kesler (1950); and Croft (1963 ). An earlier map by Hayes (1891) and maps by Butts {1946), Crickmay (1936), and the Geologic Map of Georgia {1939) would be helpful.* Acknowledgements. Part of this work was supported by the Georgia Geological Survey, and by the National Science Foundation under grant GP-3133. Jarvis B. Hadley and M. G. Croft of the U.S. Geological Survey, and A. S. Furcron and James W. Smith of the Georgia Geological Survey read the manuscript and offered many criticisms and suggestions. The Pl'oblem The validity of Kesler's correlations depends on whether the Cartersville Thrust exists and, if so, its exact location. A brief review of opinions concerning the Thrust follows. (See also Kesler's review, 1950, p. 30.). The Thrust was named by Hayes (189{) who showed it passing northward through the town of Cartersville. (See inside front cover.) Tn 1900 he published a map showing the Fault a few miles to the east. (See inside back cover.) LaForge (Hull, LaForge, and Crane, 1919, p. 53) concluded that there is no major thrust through the entire central portion of the Cartersville district where Hayes had previously shown it. LaForge thought the Fault went to the east of the district, but he published no map. Crickmay (1933) and Butts ( 1946) seem to follow the second of Hayes' interpretations with minor modifications, but because of the small scale of these maps it is difficult to compare them. Kesler (1950) decided that there is no major thrust fault at all. Croft (1963) sided with LaForge. The conclusion we must draw from this brief review is that if the Cartersville Thrust exists in the Cartersville district, no one knows where it is. Hayes (1900) and those who followed his general interpretations had one especially difficult problem in placing the Thrust. They all recognized rather pure quartzites as belonging to the Weisner Formation which is considered to be of Cambrian age. But outcrops of very similar quartzites occur at intervals far to the cast, all the way to the northwest corner of the Tate quadrangle. They had to divide these quartzites between a Cambrian part, the Weisner Formation, and a Precambrian part. Most of the Precambrian part was assigned to the Pine Log Conglomerate, the remainder to the Wilhite Formation. Efforts to differentiate the quartzite on the basis of partially carbonaceous metashales which were thought to occur in the quartzites to the east have not been successful as indicated by Croft ( 1963) who considers the shale as the middle unit of the Weisner Formation. *Many of the formational names appearing in this discussion were of local usage or are out of date. King and his colleagues (1958) have elucidated a more modern terminology in North Carolina and Tennessee. Correlations southward into Georgia arc not yet well established. 28 LaForge (1 919) and Croft (1963) ci rcumvent the quartzite problem by having the thrust trend eastward, but this interpretation is very forced as the following discussion indicates. Two graphite (carbonaceous phyllite) pits are shown by Kesler (1950 ) in the southern part of the district (See footnote below for exact locations.). He shows them in the Rome Formation, but LaForge mapped that area as the Wilhite Formation. Carbonaceous outcrops occur between the two pits. On Croft's (1963) map the pits aren't shown, but the northern pit would be located in his Cambrian Weisner Formation, and the southern pit would be located in his Precambrian Ocoee Series, and he shows the Cartersville Thrust separating them. To make matters worse, e'\len in the (sparingly) fossiliferous P aleozoic rocks, the stratigraphy is not well known. The Weisner Formation was identified by long-range correlations, and even at its type locality jn Alabama it is of uncertain age (Cressler, personal communication, 1966). L imestones and shales overlying the Weisner F ormation around Cartersville have been variously assigned to the Shady, Rome, and Conasauga F ormations. The matters mentioned above pertain directly to the problem of faulting. How little we know with certainty about the Cartersville district in general can be furthe r. emphasized by considering that the amphibolites have been interpreted as para-amphibolitcs by Kesler ( 1950) and as orthoamphibolites by Croft ( 1963). The coarsegrained gneisses of the eastern part of. the district have b een interpreted as basement material serving as a source for the overlying sediments (Hayes, 1900, p . 406) , as granitizcd sedimentary rock (Kesler, 1950, p. 20), and as an intrusive rock (Crickmay, "1936, p. 1384; Croft, 1963, p. FF7). Discussion Considering all these uncertainties, .it should not be surprising that the present author does not intend to offer a complete solution to the geological problems o f. the Cartersville district. But a few observations are in order. T he most important point is that some of the rocks generally considered to be Paleozoic can be traced into the crystalline area. This is true of the metash ale-quartzite sequence included in the Wilhite Formation by L aForge, in the Weisner and Rome Formation by Kesler, (1950) and in the Weisner Formation by Butts (1.946) and by Croft ( 1963). This sequence is easily traced all the way into the Tate quadrangle where in part it constitutes the H iwassee Formation of Bayley ( 1928). The Hiwassee Formation is interbedded with the Great Smoky Formation ( Bayley, 1928, p. 49). The equivalence of the Wilhite and H iwassee Formations ( as the names arc locally used ) apparently h as been known for a long time, and was discussed briefly by Bayley (1928 p . 51). Only Kesler (1950) has gone so far as to suggest that this fact is incompatible with Hayes' concept of a major thrust fa ult. lf the Weisner Formation (which contains part of the Wilhite Formation of earlier workers) has been correctly identified by Kesler (1950 ) , Croft (1963), and many others, and if it is really Cambrian, Hayes' (1900) second position for the F ault must be incorrect because it truncates this unit. We need to take a long, hard look at the age and correlation of the "Weisner Formation". Another point to consider is Kesler's (1950) conten tion that some of the limestones of the district grade eastward jnto shales. He is very likely correct. Hayes noted this as early a:~ 1891 (p. 148) . The critical matter is whether this graduation just involves Paleozoic rocks or whether the slightly metamorphosed shales of the adjacent P iedmont which may be Precambrian are involved. Examination of the outcrops along Georgia Route 140 which crosses the supposed Fault in the northeast part of the district suggests the reasonableness of Kesler's contention. R ocks to the west are certainly Paleozoic and consist o f shale and limestone. Eastward the limestone is Jess abundant and the shales more metamorphosed. Calcite-rich layers are found in metashales along the road well within the crystalline area. Still, a major thrust could b e concealed in the many areas lacking outcrops, and similar lithologies could be fortuitously juxtaposed on opposite sides of the fault . H ere we need detailed mapping and work on the minor minerals and microfossils, if any arc present, to test the correlation of these calcareous lithologies. The southern pit is located just weJt of the lonf(itude line 84 45', about % mile from the southern border of the map. The ot!ter pit is located about 1.75 miles to the northeast of the first. 29 The author cannot refrain from speculating about one more point. Hurst and Schlee (1962, p. 21) contend that the "Fine-grained part of the Ocoee Series" shown on Salisbury's ( 1961) map overlies the Great Smoky Group. These fine-grained Ocoee rocks arc in part equivalent to the Wilhite Formation of Hayes (Salisbury, 1961, p. 39). Furcron and Teague (1947) show a bit of the Wilhite Formation a little farther south ncar Chatsworth, and the unpublished map of LaForge shows it, with one interruption, continuing into the Cartersville district. Now remember that the Wilhite and Hiwassee Formations are equivalent in the Cartersville-Tate area. 1f Hurst and Schlee ( 1962) are correct, and if all the Wilhite as mapped along tl1e western edge of the crystalline area is the same formation, then the Hiwassee Ponnation lies ahove the Great Smoky Group and is equivalent to the Nantahala Formation. If Croft (1963) is right that the middle unit of his Weisner Formation is Cambrian and that it contains parts of the old Wilhite Formation, then the Nantahala Formation must be Cambrian. But isn't that what many people have been saying all along? But is the Wilhitc-Hiwasscc Formation really equivalent to the Nantahala Formation? Bayley's ( 1928) map would indicate it is not, yet he pointed out the similarity of the two formations (p. 63). Crickmay ( 1936, p. 1383) says they are identical and that the Hiwassee and Nantahala Formations "come together" near Waleska. The present author has traced the Formations he mapped in the Tate Quadrangle (Fairley, 1965) to the southwest, and finds that the two formations do approach each other. Despite considerab.le work, it is still uncertain if they arc actually one formation. Cross-sections can be drawn of the Tate Quadrangle making the Canton, Nantahala and Hiwassee Formations equivalent, but some weird structures must be postulated around the Salem Church Anticline in order to do so. At any rate, several lines of evidence indicate the feasibility of Kesler's interpretation of the Cartersville Thrust, and until someone can tell just where the Fault exists in the district, if it exists there, we should keep an open mind on the subject. But we arc not to conclude that there is l10 Cartersville Thrust at all. We know the Fault exists to the north of the district (Smith, 1957; Coogan and Bryan, 1963). lt probably exists to the south of the district (Cressler, in preparation). Is it reasonable then to suggest the absence of the Fault in the heart of the Cartersville district? Jt probably is. The Cartersville Thrust foJlows a highly irregular path through Georgia and Alabama as the geologic maps of those states show. lt is possible that in the Cartersville district little or no movement took place along the Fault. The Fault could be hinged in the district with abundant movement both to the north and to the south. This explanation would circumvent all the aforementioned problems. The Fault enters the District at the north along the western slope of Johnson Mountain. It could die out in the lowland to the south and pick up again along the prominent hills south of the town of Cartt:rsville. When Kesler conducted field trips over Johnson Mountain, he picked the wrong place to demonstrate the difficulties or the faulting hypotheses. If the Fault is actually hinged with little or no movement in the Cartersville district, we would be ahle to show how the movement took place and how the deformation was registered in the rocks. This can be done with a clay cake experiment which will also explain the arcuation and cross-folds mapped by Fairley (1965) in the Tate quadrangle. A few inches of soft clay arc placed upon adjacent metal plates a few inches wide and about 18 inches long. Reference lines and circles arc inscribed in the clay before deformation. If some of the strips arc slowly pulled forward at different rates while others remain stationary, the pattern shown in figure 7 develops. The circles which lie above the junctions of the plates are deformed into ellipses. Two sets of fractures form in the clay with the short axis of the ellipses, the direction of compression, bisecting them. Rocks in the :L.one of flowage would be expected to develop folds at right angles to the direction of compression rather than the sets of fractures. The arcuation in the Murphy Syncline corresponds to the lines inscribed on the clay. The lineation (crenulation as described by Fairley, 1965, p. 49) is the result of compression analogous to the compression which formed the eHipses. The relative orientations of the arcs and ellipses .in the left hand part of figure 7 should be compared with the trend of the Murphy Syncline and the crcnulations shown by Fairley ( 1965, p. 5 I). The arc (Fairley, 1965, p. 5.1) corresponds to the )eft hand portion of figure 7, and if we consider north in figure 7 to be located in the upper right corner of the page, the correspondence in orientation is apparent. The lineations at the top of the sketch map (Fairley, 1965, p. 51) do not 'fit the pattern because they are on the northeastward plunging end of the Salem Church Anticline. This experiment has provided us with an understanding of how the big arc in the Murphy Syncline formed and its relationship to the lineation. The effects of extension along the plates have not been fully 30 r Fig. ?-Photograph of clay after de/ormation. The lines were originally straight, and the ellipses were circles (1 1.4 inches in diameter). The plates moved in a directon from the bottom toward the top. investigated. The arcs on the right hand side of figure 7, if they exist jn nature at all, would correspond to areas in northern Georgia and southern North Carolina which arc not mapped in detail. 1f there are arcs in the structures to the north, then Hurst's 1955 Mineral Bluff Quadrangle occupies a location corresponding on figure 7 to the straight part of the line between arcs. Consequently he recorded a major period of folding followed by tightening of the folds, but no cross-folds (Hurst, 1955). LaForge and Phalen's map (19 I3) suggests the possibility of such arcs in northern Georgia, but the deformation plan presented here is intended primarily to explain structures in the Tate Quadrangle. The same deformation plan can account for the geology along the Cartersville Thrust. The overriding rocks did not move uniformly to the northwest. Some segments moved further than others, some may have hardly moved at all. There was thrusting through most of the Cartersville district (Kesler, 1950, p. 33) and maybe even major thrustjng. But from what we know now it is possible that in the middle of the district tbe forward movement may not have been sufficient to completely disrupt the orginal stratigraphic relationships. The trend of the Cartersville Thrust as shown on the Tectonic Map of the United States (U.S. Geological Survey and A.A.P.G., 1962) should be examined to better visualize what the author has in mind. Another Way to Look at the Problem The substance of the preceding argument is this: that many of the rock units thought to lie west of the Cartersville Thrust (including fossiliferous rocks of known Cambrian age) are very similar, and perJ1aps equivalent to rock units of the Piedmont on the eastern side of the supposed thrust. So the posHion nnd very existence of the fault are in doubt. The most extensive nearby work concerning the tectonic and stratigraphic relationships between Piedmont and Valley and Ridge rocks is that of King and his colleagues in Tennessee (Hamilton, 1961; Hadley and Goldsmith, 1963; King, 1964; Neuman and Nelson, 1965). King's (1964, p. 60) regional map shows the Chilhowee and Walden Creek Groups in the Cartersville district. This is, of course, an extrapolation based on reconnaissance work, and must be so considered . Specifically, King suspects that the pure quartzites are part of the Chilhowee Group, and the carbonates mapped by Kesler (1950) at the Cartersville Dam are part of the Walden Creek Group (personal communication, Dec., 1965) . The relationships between the Chilhowee, Walden Creek and Great Smoky Groups are obscured by complex faulting and jntertonguing, but the Chilhowee is probably largely younger than the Walden Creek which in turn is at least partly younger than the Great Smoky Group. The Wilhjte F ormation of the older literature on the Cartersville district js a typical lithology of the Walden Creek Group. Recalling that the Wilhite Formation is in part equivalent to the Hiwassee Formation of Bayley ( 1928) which he mapped under the 31 Great Smoky Group, it appears that King's suggestion further obscures the already confused relationship~ among these rocks. However, the results of our geologic mapping can be interpreted in a way to resolve the appare.nt difficulties, and this interpretation is given helow. First the reader should note the following features shown on the geologic map in this guidebook (outside of back cover) : 1. The NuntahaJa Formation pinches out Jarther to the north on the east side of the Murphy syncline, than on the west side. 2. Rocks of the Great Smoky Group appear farther south than those of the Nantahala Pormation on the east limb, but they thin or pinch out on both limbs. 3. The attitude of tl1e bedding is not para11c1 to the lithologic trends in the area west of the nose of the Salem C hurch Anticline. This is also true in the hilly area sou th or the town of Cartersville as can be seen by comparing th~ lithologic trends shown on Croft's ( I963) map with the structure symbols shown on Kesler's (1950) map. Apparently the difkrcnt lithologies interfinger. 4. Quartz sandstones are more prominent to the west, carbonaceous metashale to the east in the westernmost unlt shown on the map. These meager facts with a few not indicated on the map may be developed into an hypothesis wh ich, though tenuous, will serve as a point of departure for discussions in the field. The hypothesis embraces the idea that the Late Precambrian and Early Cambrian sediments in northern Georgia can be divided into two very different areas of depositional environments and with separate sources. The Great Smoky Group was deposited rapidly in an actively subsiding basin and was supplied from high-standing land masses to the northeast and perhaps to the cast (King, 1964, p. 68-70). This basin extended from the present site of tlte Great Smoky Mountains southwestward to the vicinity of Cartersville. The basement gneisses, now partially cxpo~ed, (Corbin and Salem Church Granites) constituted a highland which terminated the basin, or at least interrupted it. We don't know if Great Smoky lithologies continue to the southwest of Cartersville, but they probably don't. This basin shoaled to the west and eventually terminated against a stable low-lying land mass. The nature of the sedimentary clebris derived from this land mass is in marked contrast with tltat which filled the Great Smoky basin. The Great Smoky rocks are poorly sorted texturally and compositionally. Many are graywackes and shales (Hurst, 1955b; Fairley, l965) and are typically eugcosynclinaJ except in being nearly devoid of volcanic components. The sediments from the stable land m<~ss are mostly cleanly washed with quartz sandstone prominent to the west near the old shore line and shales prominent to the east. Abundant carbonaceous phyllite indicat~s some of the shales accumulated in a r~ str.icted environment. Local fine-grained conglomerates constitut~.; an exception to the cleanly-washed material. The conglomerates contain many small fragments rich in potassium feldspar, and as suggested by Hayes (1900, p. 406) were probably derived from feldspathic gneisses which stood as islands above the l~vcl of the ocean. The Hiwassee rocks were an early deposit derived from a stable land mass, or craton. Tn part they underlie the western portion of the Great Smoky Group, but they also intertongue with it as indicated by the angle between the lithologic and structural trends on the northwest flank of the Salem Church Anticline. The Hiwassee material probably did not extend fat to the east as we don't :iind any complete counterpart of it on the eastern limb of the Murphy Syncl.inc. The Canton Formation, although of short extent, may be its equivalent. Deposition of the Great Smoky sediments was probably very rapid, but when completed th~.; sediments from the craton were still accumulating and may have covered the western portions of the Great Smoky Group. These late cratonic sediments west of the Salem Church Anticline include the Scolithus-bearing quartz sandstone of the Weisner Formation. Carbonates of the Great Valley were deposited on the quartz sandstones. On the cast limb of the anticline the Gr.eat Smoky Group is covered by the Nantahala f ormation although its stratigraphic relationship to the Weisner Formation is not known. The Nantahala Formation lies directly on the Hiwassee Formation where the Great Smoky was not deposited at the south end of the basin. That is why they come together and appear to be one formation. 32 In brief then, it appears tl1at the "Weisner-Wilhite-Hiwassee" coterie is in part older than the Great Smoky Group, in part equivalent to it, and in part younger than it, and they intergrade and intertongue complexly. An excellent example of intergrading of this general sort was pre:scnted by Salisbury (1961, p. 23). He found quartzites of possible Chilhowee affinity grading into subgraywaches typical of rocks he assigned to the Ocoee Group. He thought this meant that the quartzites did not belong to the Chilhowee Group. But from the above discussion it would seem reasonable to have rocks of one gro up grading into rocks of another group. The problem of whether any of the rocks in Salisbury's area correspond to the W a lden Creek Group in the Great Smoky Mountains still persists, however. We must still consider the possibility that the f.ault exists between carbonates and a quartzite ncar the south end of the district. The Shady dolostone normally overlies the Chilhowee sandstones in Tennessee and elsewhere. However, quartz sandstones physica lly overlie the carbonates at many places in the district as at the quarries near the intersection of routes U.S. Route 41 and Ga. Route 293 and perhaps in quarries west of this intersection. Croft's ( 1965) map shows this as due to overturning of a large fold near and west of Allatoona dam. But the extensive area over which the revenal can be intermittenly observed suggests the additional possibility of thrusting. This is especially interesting if. the quartzites belong to the Chilhowee Group and if tlle carbonates belong to the Shady F ormation (see Crort's 1963 map). Al the northwest end of Chilhowee Mountain the Chilhowee Group is thrust over the Shady Formation on the Great Smoky Thrust, the no rthern counterpart of the Cartersville Thrust. If the Cartersville Thrust does exist between the quartz sandstones and the carbonates, the stratigraphic succession may not be markedly disturbed. The sandstone-carbonate sequence may occur in an overturned anticline in places as suggested by Croft (1963), while the fold is broke n and slightly displaced in others. Tn any case, correlations between rocks of the Valley and Ridge and the Piedmont may yet be made when sufficient mapping has been done. H owever, the formational terminology used by Kesler (1950), Croft (1963) and all the earlier workers must be unified and brought up to date. Comments by A. S. Furcron 1 received your. letter of July 1 and the manuscript which you have written on the Cartersville Thrust at Cartersville, Georgia. I decided to take it home and read it but after reading the first couple of pages, 1 finished reading it at one sitting at my desk. It is interesting and provocative. l do not feel qualified, however, to criticize articlcs upon the Cartersville Fault. This "Fault" has been in debate since it was announced, and I am sure that the debate will go on for a .long time. There are many ways of writing a paper about a regional area in geology where certain interpretations are subject to question. Some writers attempt to prove other workers wrong; some attempt to prove some were right and 50rne wrong or that the above writers were both right and wrong, partly or locally but that m any other alternatives, some already suggested, may be re-combined with numerous observations made by others a nd the author, which will suggest an acceptable explanation. T hat approach generally stirs things up so thoroughly that it appears to make it desirahlc to close the books and make a new start on everything. I have always regarded the Cartersville Fault as not a "Fault" solely in and by itself as representing one great structu ral move ment made at one time but as a series of imbricate thrusts where only the outcropping edge can be studied and that the thrusting movement may be greater and more complicated in some places than in others or that indeed, it might possibly be absent. In the valley of Virginia, I l1ave seen well defined in a road cut, the Precambrian hypersthene granodiorite thrust directly over the thick Cambrian limestone series. l wouldn't know if this is a direct extension of the Cartersville Fault but we dm.1bt it; however, 1 would regard it as thrusting in the same structural zone or geologic locality as the Cartersville Fault. Another trouble about the C artersville Fault problem is, that in general it has been like the blind men and the elephant, each man describing tl1c elephant from the particular portion which he was able to touch and feel. How far should we continue to follow the Cartersville Fault before we draw definite conclusions upon it? Also, 33 should we continue to call it the Cartersville Fault, if it actually does not extend for a great distance, because it is not very close to Cartersville. As you can sec, I am merely rambling along with ideas that come to mind and adding nothing particular to the problem. H ow far may we trace the Nantahala and in how many different directions and where does structure enter into that problem? How do we know that the black slate, ~o prominent south of' the fault line in Polk County south of Cedartown, is not Nantahala? There is much of it there and l have not heard of anyone suggesting that possibility before. On the Ellijay and Murphy Folios, the Nantahala is a regular well behaved formation of black slate between the Murphy Series and the ''Great Smoky Formation" on the west side, and the Carolina Gneiss on the cast side but when you go further north and begin to examine this Formation on the Nantahala F<.llio, a great many questions arise about it. For example, on the EIHjay Folio, from the Cartersville Fault eastward to the Murphy Syncline jn rocks which have been mapped as both Great Smoky and Ocoee, there arc repeated .large deposits of black s late. They arc folded and not too much has happened to them but there is progre~sive mctamorphiRln. in the "Great Smoky" eastward from the Cartersville Fault from small biotite porphyroblasts through garnet, genal rt. do.tum,meu tea-leTel OEOLOOt CAL MAP OF THE CARTERSVt\.I.E Oti!TRICT, GEORGIA. Map of Hayes 1900 0 Boliv "? ar White 0 o Car teravllle .. :::: ,- -- ,r Sketch Map of the Geology l)etween Tate and Cartersville, Georgia Scale in miles 5 0 5 HF3H I 7 - 'nT..:'""';.; ;"' A ~ Murphy Marble. l EGENO ~ ~ Brasstown and Andrews Formations. omo Nontahala Formation. c=J Great Smoky Group . ~ Canton Formation. m3IH Gneiss. (Corbin and Salem Church Granites) ~ Orthoquartzites (largely to the west) and metashales (largely to the east). MetaahoJes in places carbonaceous. Carbonate lenses widespread, especially in the metashale$. Parts of the sequence are of questionable, and probably variable, stratigraphic position. Compled from Fairley, \965 a unpublished data; Kesler, 1950; r- Strike and dip of beda_ a La For;e, unpublished; Smith, 1957. ~ Carternille thrust. + Murphy Syncline. ~ + Salem Church Anticline. ~~ ~ !