Burial and Thermal History of the Central 

Appalachian Basin, Based on Three 2-D Models 

of Ohio, Pennsylvania, and West Virginia 

By Elisabeth L. Rowan 

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U.S. Geological Survey 
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copyright owners to reproduce any copyrighted material contained within this report. 
BURIAL AND THERMAL HISTORY OF THE CENTRAL APPALACHIAN BASIN, 


BASED ON THREE 2-D MODELS THROUGH OHIO, PENNSYLVANIA, AND 


WEST VIRGINIA 


Elisabeth L. Rowan 


U.S. Geological Survey 


12201 Sunrise Valley Dr., M.S. 956


Reston, VA 20192 


INTRODUCTION 

Three regional-scale, cross sectional (2-D) burial and thermal history models are presented 

for the central Appalachian basin based on the detailed geologic cross sections of Ryder and 

others (2004), Crangle and others (2005), and Ryder, R.T., written communication. The 

models integrate the available thermal and geologic information to constrain the burial, 

uplift, and erosion history of the region. The models are restricted to the relatively 

undeformed part of the basin and extend from the Rome trough in West Virginia and 

Pennsylvania northwestward to the Findlay arch in Ohio (Fig. 1). This study expands the 

scope of previous work by Rowan and others (2004) which presented a preliminary 

burial/thermal history model for a cross section (E-E') through West Virginia and Ohio. In 

the current study, the burial/thermal history model for E-E' is revised, and integrated with 

results of two additional cross sectional models (D-D' and C-C'; Fig. 1). 

The burial/thermal history models provide calculated thermal maturity (Ro%) values for the 

entire stratigraphic sequence, including hydrocarbon source rocks, along each of the three 

cross sections. In contrast, the Ro and conodont CAI data available in the literature are 

sparse and limited to specific stratigraphic intervals. The burial/thermal history models also 

provide the regional temperature and pressure framework that is needed to model 

hydrocarbon migration. 
MODEL ASSUMPTIONS 


The burial/thermal history models simulate sediment accumulation, compaction, uplift, 

and erosion, as well as temperatures and thermal maturities through time. The modeling 

approach discussed in Rowan and others (2004) is utilized also in the models presented 

here and the text below focuses on revisions and additions to the earlier study. The most 

significant changes include a revision in the basement heat flow value specified in the 

models and the addition of bottom hole temperature (BHT) data to calibrate the models. 

Heat Flow 

The initial model of section E-E' (Rowan and others, 2004) used a heat flow of 60 mW/m2, 

consistent with the heat flow assumed in study of western Pennsylvania (Cercone and others, 

1996). The models presented here, including the revised model of E-E', use a heat flow of 52 

mW/m2

 based on a recent map-based heat flow compilation for North America (Blackwell 

and Richards, 2004). The revised heat flow value is considered to be a better representation 

of basement heat flow across the study area. For comparison, the average surface heat flow 

for the North American continent is reported to be 54.4 mW/m2

 and the global continental 

average to be 56.6 mW/m2

 (data from Sclater and others, 1980, see Allen and Allen, 1990, 

Table 2.2). 

Bottom Hole Temperatures 

Bottom hole temperature (BHT) data for 28 of 31 wells were compared with modelcalculated temperature-depth profiles and were used to calibrate the models. BHT 

corrections were made using the equations of Waples and others (2001, 2004a, b). 

Model-calculated temperature profiles and corrected BHT data are shown in Figure 2 for 

the deepest wells on sections C-C' and E-E', the Svetz and Gainer-Lee wells, respectively. 

These profiles are typical of the 28 wells for which BHT data were available in that they 

show fair to good overall agreement between the model and corrected BHT data although 

2

a small number of outlying data are not matched by the model. The inclusion of BHT 

data represents a significant improvement over the previous model (Rowan and others, 

2004) because these data permit verification that the models’ thermal parameters (heat 

flow, surface temperature, and lithology-specific thermal conductivities) reproduce 

measured, present day temperatures. 

Lithologies and their Properties 

Lithologies are defined for each model unit in 26 of the 31 wells for which lithologic logs 

were available (Table 1). In wells for which logs were not available, average lithologies 

were determined based on the lithologies of the neighboring wells. This approach 

provides more detail than in the earlier version of model E-E' (Rowan and others, 2004) 

in which lithologies of each model unit were averaged over the cross section. The 

physical properties of individual lithologies are unchanged from the earlier study (Rowan 

and others, 2004). 

Thermal Maturity 

Throughout this report thermal maturity is quantified in terms of vitrinite reflectance (Ro%), 

whether or not vitrinite or other organic matter is actually present; thus, a few words of 

explanation may be helpful to the reader. Vitrinite reflectance (Ro%) is one of numerous 

indicators of thermal maturity and like all such indicators it increases both with time and 

temperature. Ro data have been collected widely from vitrinite samples from sedimentary 

basins worldwide, including the Appalachian basin. Vitrinite reflectance is perhaps the most 

commonly measured and widely quoted thermal maturity parameter, and serves as a de facto 

reference scale for the thermal maturity of organic matter. Ro% values of approximately 0.6 

and 1.4, respectively, mark the approximate onset of oil generation and the shift from 

predominantly oil to predominantly gas generation in oil-prone source rocks. The range, 

0.06 Ro%1.4, is referred to as the "oil window" or thermal maturity range for significant 

oil generation in oil-prone source rocks. Ro% values between approximately 1.4 and 3.0 

3

represent the "gas window" or maturity range for thermal generation of hydrocarbon gases 

(see for example, Kübler, B., and Jaboyedoff, M., 2000, Fig. 8). 

The terms "oil window" and "gas window" are widely used, but they should be used with 

caution because the equations used to calculate vitrinite reflectance incorporate a number of 

assumptions, including kerogen type and the kinetics of the transformation reactions 

(Sweeney and Burnham, 1990). In this report these terms terms are used to give only a 

general indication of thermal maturity level with respect to oil or gas generation. Vitrinite 

reflectance is readily calculated in numerical models allowing Ro% values to be predicted 

for strata throughout the model domain and through time. 

Restoration of Eroded Strata 

Numerous authors have noted that that thermal maturity measurements made in Paleozoic 

strata in the Appalachian basin require significantly greater burial depths and temperatures 

than are present today (e.g., Epstein and others, 1977; Cercone and others, 1996; Hulver, 

1997; Reed and others, 2005). As in earlier models, the temperature ranges required to 

match measured temperatures and thermal maturities are attained in the current study by 

restoring the sediment thicknesses at maximum burial. Permian sediments comprise the 

majority of the strata restored in the models, but smaller amounts Pennsylvanian and older 

units were restored where they were eroded on the Findlay arch, based on regional trends in 

stratigraphic thickness. The model stratigraphic units for section D-D' (representative also of 

section C-C' and E-E') are shown at maximum burial (Fig. 3) and in present day, post-erosion 

configuration (Fig. 4). The individual formations that comprise the model units are listed in 

Table 2. Thicknesses of the restored units at individual wells at maximum burial and present 

day are shown graphically in Figure 5. In model C-C', which terminates farthest to the 

southeast and closest to the basin depocenter, a maximum of 12,500 ft of Permian and 

Pennsylvanian strata were restored (Fig., 1; Fig. 5a). For comparison, Reed and others (2005) 

estimated that burial of burial of Pennsylvanian strata on the Allegheny Plateau in West 

Virginia exceeded ~4.4 km (14,432 ft) in the mid Permian. Similarly, Hulver (1997, Fig. 

4

8.06) estimated 4.5 – 5 km (14,760 – 16,400 ft) of erosion along the Allegheny structural 

front in West Virginia and Pennsylvania since the end of the Allegheny Orogeny. 

In an earlier version of model E-E’, Rowan and others (2004), specified that maximum 

burial occurred during the mid-Triassic (230 Ma), consistent with the timing of maximum 

burial assumed by Ryder and Zagorski (2003). In the current study, this timing is revised to 

approximately match the results of Reed and others (2005) who combined (U-Th)/He and 

apatite fission track dating methods with paleotemperatures from fluid inclusions and 

vitrinite reflectance to define an uplift and erosion history of the Appalachian Plateau of 

West Virginia. In models C-C', D-D', and E-E' presented here, maximum burial occurs 

during the mid-Permian (270 Ma) and is followed by steady erosion until present day. 

Each cross-sectional model (C-C’, D-D’, and E-E’) specifies the thickness of Permian strata 

during maximum burial, with the greatest thickness to the southeast and thinning 

northwestward. The thicknesses of restored Permian strata were adjusted to match the 

following thermal maturity data: 1) vitrinite reflectance (Ro%) measurements on 

Pennsylvanian coals, 2) reflectance (Ro%) measurements of dispersed vitrinite in the 

Devonian Marcellus Shale, and 3) color alteration index (CAI) values measured in conodonts 

in the Devonian Onondaga and Ordovician Trenton-Black River limestones (Hower, 1978; 

Cole and others, 1979; Rimmer, 1985; Chyi and others, 1987; Hower and Rimmer, 1991; 

Repetski and others, 2002, 2004, 2005). Model-calculated vitrinite reflectance-depth profiles 

for the Gainer-Lee and Svetz wells are shown in Figure 6 with Ro% and CAI data from the 

vicinity of the wells superimposed. As with the BHT data discussed above, the modelcalculated Ro-depth profiles are in fair to good overall agreement with the thermal maturity 

measurements, however, a small number of data are not matched by the model. 

MODEL RESULTS 

The results of the burial history models are presented in several ways, 1) over the entire 2D 

model domain at present day (Fig. 7), and 2) for a several key hydrocarbon source rock units 

5 
over the length of the cross section and through time (Figs. 8-10). Figure 8 shows profiles of 

thermal maturity (shown as vitrinite reflectance, Ro%) for the Ordovician 'Utica' model unit 

(comprised almost entirely of Utica Shale) along cross sections C-C', D-D' and E-E' at 

present day and at selected earlier times. In this figure, the Utica Shale reached thermal 

maturity (i.e., entered the oil window) as early as Middle to Late Devonian time (360 – 390 

Ma) in wells located in the deepest portion of the basin in Pennsylvania and West Virginia. 

Thus, from Middle – Late Devonian onward there was the potential for Utica-sourced 

hydrocarbons to migrate through the basin. The Utica Shale reached thermal maturity at 

progressively younger ages from southeast to northwest due to the decreasing overburden 

thickness away from the basin depocenter. At wells located near the crest of the Findlay arch 

the model predicts a thermal maturity for the Utica Shale below that of the oil window. 

Similar figures show the evolution of thermal maturity through time for the base of the 

Devonian 'Ohio Shale' model unit (Fig. 9) and the base of 'Pennsylvanian' model unit (Fig. 

10). The 'Ohio Shale' model unit is comprised primarily of Upper Devonian Shales of which 

the Ohio Shale is among the thickest. The 'Pennsylvanian' model unit includes all strata of 

Pennsylvanian age (see Table 2). According to the burial/thermal history models, the base of 

the 'Ohio Shale' model unit was in the oil window as early as the close of Mississippian (320 

Ma) in the deepest parts of the basin (sections C-C' and D-D', Pennsylvania and West 

Virginia; Figs. 9a, b) and could have generated hydrocarbons from that time forward. 

The model results indicate that the base of the Pennsylvanian strata entered the oil window 

(Ro% > 0.6) as early as mid-Permian time (270 – 280 Ma) at the southeastern ends of cross 

sections C-C', D-D', and E-E' (Fig. 10). 

ACKNOWLEDGEMENTS 

The author wishes to thank James Coleman, John Repetski and Christopher Swezey who 

shared their insights and knowledge of the Appalachian basin geology in numerous 

conversations. The contributions of Robert Crangle, Rebecca Hope, Erika Lentz, and 

6

Michael Trippi who worked with Robert Ryder to define and compile the stratigraphies used 

in this study are also acknowledged. Thoughtful reviews provided by Christopher Swezey 

and Robert Ryder improved the manuscript. Finally, the author wishes to gratefully 

acknowledge Robert Ryder who generously shared his vast knowledge of Appalachian basin 

geology and who has contributed greatly to this study. 

REFERENCES 

Allen, P.A., and Allen, J.R., 1990, Basin Analysis, Principles and Applications, 

Blackwell Science, Oxford, U.K., 451 p. 

Blackwell, D.D., and Richards, M.C., 2004, Geothermal Map of North America, 

1:6,500,000 scale, 1 sheet, AAPG, Tulsa, OK, http://bookstore.aapg.org/. 

Cercone, K.R., Deming, D., and Pollack, H.N., 1996, Insulating Effects of Coals and 

Black Shales in the Appalachian Basin, Western Pennsylvania, Organic 

Geochemistry, v. 24, 243-249. 

Chyi, L.L., Barnett, R.G., Burford, A.E., Quick, T.J., and Gray, R.J., 1987, Coalification 

patterns of the Pittsburgh coal: their origin and bearing on hydrocarbon 

maturation: International Journal of Coal Geology, v. 7, p. 69-83. 

Cole, G.A., Williams, D.A., and Smith., C.J., 1979, Regional coalification patterns for the 

coals of eastern Kentucky, West Virginia, Ohio, Maryland, and southern 

Pennsylvania, West Virginia Geological Survey Open File Report 57, 28p. 

Crangle, R. D., J., Ryder, R.T, Trippi, M. H., Swezey, C. S., Lentz, E. E., Rowan, E. L., 

and Hope, R. S., 2005, Geologic Cross Section (D-D') through the Appalachian 

Basin from Sandusky County, Ohio, to Hardy County, West Virginia: AAPG 

Eastern Section, Morgantown, West Virginia, September 18-20, 2005, Abstracts, 

p. 19-20, AAPG Bulletin v. 89. 

Epstein, A.G., Epstein, J. B., and Harris, L., 1977, Conodont color alteration -- an index 

to organic metamorphism: U.S. Geological Survey Professional Paper 995, 27 p. 

Hower, J.C., 1978, Anisotropy of vitrinite reflectance in relation to coal metamorphism 

for selected United States coals, Doctoral Dissertation, Pennsylvania State 

University, University Park, PA, 356 p. 

7 
Hower, J., C., and Rimmer, Susan M., 1991, Coal rank trends in the Central Appalachian 

coalfield: Virginia, West Virginia, and Kentucky: Organic Geochemistry, v. 17, 

no. 2, p. 161-173. 

Hulver, M.L., 1997, Post-Orogenic Evolution of the Appalachian Mountain System and 

its Foreland: Chicago, Illinois, University of Chicago, Ph.D. dissertation, 1055 p. 

Kübler, B., and Jaboyedoff, M., 2000, Illite Crystallinity: C.R. Acad Sci. Paris, Sciences 

de la Terre et des planetes / Earth and Planetary Sciences, v. 331, p. 75-89. 

Reed, J.S., Spotila, J.A., Eriksson, K.A., and Bodnar, R.J., 2005, Burial and exhumation 

history of Pennsylvanian strata, central Appalachian basin: an integrated study: 

Basin Research, v. 17, p. 259-268. 

Repetski, J. E., Ryder, R. T., Harper, J. A., and Trippi, M. H., 2002, Thermal Maturity 

Patterns (CAI and %Ro) in the Ordovician and Devonian Rocks of the 

Appalachian Basin In Pennsylvania, USGS Open File Report 02-302, 57 p. 

Repetski, J.E., Ryder, R.T., Weary, D.J., and Trippi, M.H., 2004, Thermal Maturity 

Patterns for Ordovician and Devonian Rocks of the Central Appalachian Basin, 

Based on CAI and %Ro, Geological Society of America, Abstracts with 

Programs, v. 36, no. 2, p. 147. 

Repetski, J. E., Ryder, R. T., Avary, K. L., and Trippi, M. H., 2005, Thermal Maturity 

Patterns (CAI and %Ro) in the Ordovician and Devonian Rocks of the 

Appalachian Basin in West Virginia, USGS Open File Report 2005-1078, 69 p., 

http://pubs.usgs.gov/of/2005/1078/ 

Rimmer, S.M., 1985, Lateral and vertical variability in petrography and mineralogy of 

the lower Kittanning Seam, western Pennsylvania and eastern Ohio, Doctoral 

Dissertation, Pennsylvania State University, University Park, PA, 502 p. 

Rowan, E.L., Ryder, R.T., Repetski, J.L., Trippi, M.H., and Ruppert, L.F., 2004, Initial 

results of a 2D burial/thermal history model, central Appalachian basin, Ohio and 

West Virginia: U.S. Geological Survey Open File Report 2004-1445, 37 p. 

Ryder, R.T., and Zagorski, W.A., 2003, Nature, origin, and production characteristics of 

the Lower Silurian regional oil and gas accumulation, central Appalachian basin, 

United States: AAPG Bulletin, v. 87, no. 5, p. 847-872. 

Ryder, R.T., Swezey, C.S., Crangle, R.D., and Trippi, M.H., 2004, Geologic Cross 

Section Through the Appalachian Basin from the Findlay Arch, Northwestern 

Ohio, to the Allegheny Structural Front, Eastern West Virginia, AAPG Eastern 

Section Meeting October 3-5, 2004, Columbus, Ohio, AAPG Bulletin, Vol. 88, 

No. 13 (supplement). 

8 
Sclater, J.G., Jaupart, C., and Galson, D., 1980, The heat flow through oceanic and 

continental crust and the heat loss of the earth: Reviews of Geophysics Space 

Physics, v. 18, p. 269-311. 

Sweeney, J.J., Burnham, A.K., 1990, Evaluation of a simple model of vitrinite reflectance 

based on chemical kinetics: American Association of Petroleum Geologists 

Bulletin, v. 74, p. 1559-1570. 

Waples, D.W., and Ramly, M., 2001, A statistical method for correcting log-derived 

temperatures: Petroleum Geoscience, v. 7, p. 231-240. 

Waples, D.W., Pedersen, May Ritt, and Kuijpers, Peter, 2004a, Correction of single logderived temperatures in the Danish Central Graben, North Sea: Natural Resources 

Research, v. 13, p. 229-239. 

Waples, D.W., Pacheco, Jorge, and Vera, Alfredo, 2004b, A method for correcting logderived temperatures in deep wells, calibrated in the Gulf of Mexico: Petroleum 

Geoscience, v. 10, no. 3, p. 239-245. 

9

Table 1. Location and other information for wells used in constructing models C-C', D-D', and E-E' 

(data sources: Crangle et al., 2005, Ryder et al., 2004, and Ryder, R.T., written communication). 

Model 

Well 

No. 

Short 

Name Lease Name State County Latitude Longitude API (from State) 

Lithologic 

Log 

Available 

Model C - C' 

1 Krysik Krysik-Wakefield et al. OH Erie 41.30430 -82.35046 34-043-20011 yes 

2 Born A. & A. Born OH Lorain 41.28930 -82.32085 34-093-20794 yes 

3 Smith F.L. Smith Estate OH Medina 41.22891 -81.70270 34-103-21143 yes 

4 Westfall B. Westfall OH Stark 40.95247 -81.26263 34-151-21081 yes 

5 Murray Frank Murray OH Columbian 40.78578 a -80.87042 34-029-20648 yes 

6 Minesinger S. Minesinger WV Hancock 40.53972 -80.55611 47-029-00080 yes 

7 Ashcroft Richard J. Ashcroft PA Beaver 40.60155 -80.43412 37-007-20060 yes 

8 Ricks E. C. Ricks PA Fayette 39.84346 -79.65427 37-051-20056 yes 

9 Svetz Leonard Svetz PA Somerset 39.97776 -79.33387 37-111-20045 yes 

Model D - D' 

1 Haff V. & I. Haff OH Sandusky 41.37085 -82.90661 34-143-2-0077 yes 

2 Kerbel Paul Kerbel OH Sandusky 41.43770 -83.31652 34-143-20147 yes 

3 Wheeler I.M. Wheeler OH Huron 41.10610 -82.70442 34-077-2-0025 no 

4 Empire Empire Reeves Steel Div. OH Richland 40.77921 -82.51903 34-139-20448 yes 

5 Drake Alonzo Drake, Jr. OH Wayne 40.86050 -81.90569 34-169-2-1419 yes 

6 Troyer Dan E. Troyer OH Holmes 40.65712 -81.77225 34-075-21283 yes 

7 Huebner Huebner OH Tuscarawas 40.30405 -81.42453 34-157-21030 yes 

8 Zechman Thomas Zechman OH Harrison 40.19500 -81.19717 34-067-2-0737 no 

9 Birney Roy Birney OH Harrison 40.26188 -80.96636 34-067-20103 yes 

10 Burley John Burley WV Marshall 39.76167 -80.53000 47-051-00539 yes 

11 Finch R.R. Finch WV Marion 39.43194 -80.01222 47-049-00244 yes 

Model E - E' 

1 Carter Carter OH Wood 41.41492 -83.60898 34-173-20237 yes 

2 Kerbel Paul Kerbel OH Sandusky 41.43770 -83.31652 34-143-20147 yes 

3 Asphalt M. and B. Asphalt Co. OH Seneca 41.22640 -83.19891 34-147-60840 no 

4 Leonhardt V.E. Leonhardt OH Crawford 40.90996 -82.88333 34-033-20050 no 

5 Windbigler A.C. Windbigler OH Morrow 40.69033 -82.68222 34-117-20047 yes 

6 Palmer J. Palmer OH Richland 40.64802 -82.58955 34-139-20289 yes 

7 Lee Edwin L. Lee OH Coshocton 40.32292 -82.00095 34-031-22053 yes 

8 Marshall W. R. Marshall OH Guernsey 40.03672 -81.72047 34-059-20782 yes 

9 Ullman Robert Ullman OH Noble 39.61067 -81.34730 34-121-21278 yes 

10 Deem Howard H. Deem et ux WV Wood 39.08057 -81.50795 47-107-00756 yes 

11 McCoy Walter McCoy et al. WV Jackson 38.73055 -81.56944 47-035-01366 yes 

12 Gainer-Lee Gainer-Lee WV Calhoun 38.87500 -81.09760 47-013-02503 no

 10

11


Table 2. Model unit names and ages, and stratigraphic units (groups, formations and members of formations) that comprise themodel units. Bold type indicates a stratigraphic unit for which the model unit was named. Stratigraphic information is based on Crangle et al. (2005), Ryder et al. (2004), and Ryder, written communication. Not every stratigraphic unit is present in everywell. Model unit ages approximate the formation ages defined in Ryder et al. (2004). Abbreviations are listed at the end of the table. 

Age 

Age of top

of model

unit (m.y.) 

Model unit name Formations 

Permian 270 'Permian' Dunkard Gp

Pennsylvanian 300 'Pennsylvanian' 

Monongahela GpConemaugh Gp (incl Mahoning Ss)

Allegheny Gp

Pottsville Gp (incl Kanawha Fm, New River Fm & Sharon Congl)

Mississippian 320 'Mississippian' 

Mauch Chunk FmGreenbrier Ls, Maxville Ls, Wynps LsLoyalhanna Fm, Logan FmCuyahoga Fm (incl Big Injun Ss & Weir Ss), Price Fm, Shenango Fm &Burgoon SsSunbury Shale, Berea Ss

Devonian 360 'Ohio Shale' 

Bedford Sh, Upper Devonian strata undiv, Cussewago Ss, Riceville Fm &Hampshire FmOhio Sh (incl Cleveland Mbr, Three Lick Bed, & Huron Mbr), Chagrin Sh,Venango Gp, Greenland Gap (Foreknobs) Fm, Chadakoin Fm, Bradford Gp,Elk Gp, Perrysburg Fm (Dunkirk Mbr), Braillier FmOlentangy Sh (upper), Java Fm

Devonian 375 'Rhinestreet' 

West Falls Fm (Angola & Rhinestreet Mbrs)

Sonyea Fm (incl Cashaqua Sh & Middlesex Sh Mbrs), Genessee Fm (inclWest River Sh & Genneseo Mbrs), Harrell Sh, Tully LsPlum Brook Sh, Prout Ls, Olentangy Sh (lower), Hamilton Gp (inclMahantango Fm, Marcellus Sh) 
Table 2 cont.


Age 

Age of top

of model

unit (m.y.) 

Model unit name Formations 

Devonian 390 'Onondaga' 

Delaware Ls, Columbus Ls, Onondaga Ls, Huntersville Chert, Detroit River

Gp

Bois Blanc Fm, Oriskany Ss, Ridgeley Ss, Hillsboro SsHelderberg Ls, Licking Creek LsMandata ShKeyser Ls (upper; Corriganville / New Creek Ls)

Silurian 415 'Salina' 

Bass Islands Dol, Big Mountain Sh

Keyser Ls (lower)

Salina Gp, Tonoloway Ls, Wills Creek Fm, Bloomburg Fm

Silurian 420 'Lockport' Lockport Dol, Tymochtee & Greenfield Dols undiv, McKenzie Ls, Keefer SsSilurian 425 'Medina' 

Rose Hill Fm (incl Cacapon Mbr), Rochester Sh, Mifflintown Fm (McKenzie& Rochester Mbrs), Dayton LsCabot Head Sh, "Clinton" Ss, Medina Ss, Tuscarora Ss (incl Castanea Mbr)Brassfield Ls, Manitoulin Dol

Ordovician 445 'Reedsville' Queenston Sh, Juniata Fm, Oswego Ss Whitewater Fm, Cincinnati Gp undiv, Reedsville Sh 

Ordovician 450 'Utica' Utica Sh, Antes Sh, Trenton Ls (upper)

Ordovician 455 'Trenton' 

Trenton Ls, Trenton Gp (incl Coburn & Salona Fms)

Black River Ls, Black River Gp (incl Linden Hall, Snyder, & Hatter Fms)

St Paul Gp (incl Loysburg Fm) 

12

13


Table 2 cont.


Age 

Age of top

of model

unit (m.y.) 

Model unit name Formations

Ordovician -

Cambrian 460 'Beekmantown' 

Wells Creek Fm, Row Park LsBeekmantown GpGatesburg Fm (incl Mines & Ore Hill Mbrs)Knox Dolomite (incl Rose Run Ss & Kyrsik Ss), Copper Ridge Dol

Cambrian 495 'Conasauga' 

Kerbel FmEau Claire Fm, Conasauga Gp (incl Nolichucky Sh, Maryville Ls)Mt. Simon

Cambrian 510 'Rome trough' 

Conasauga Gp (incl Rogersville Sh, Rutledge Ls, Pumpkin Valley Sh)Rome (Waynesboro) FmShady Dol, Tomstown Dol

Warrior Fm, Pleasant Hill Fm, Waynesboro Fm

Tomstown Fm

Precambrian 520 'Basement' Igneous/metamorphic basement rocks

Abbreviations:

Gp Group 

Fm Formation 

Mbr Member 

Congl Conglomerate

Ss Sandstone 

Sh Shale 

Ls Limestone 

Dol Dolomite incl including 

undiv undivided 
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