U.S. Department of the Interior

U.S. Geological Survey

Pamphlet to accompany

Scientific Investigations Map 3425

Geologic Cross Section A–A′ Through the Appalachian Basin From the 

Southern Margin of the Ontario Lowlands Province, Genesee County, 

Western New York, to the Valley and Ridge Province, Lycoming County, 

North-Central Pennsylvania

By Michael H. Trippi, Robert T. Ryder, and Catherine B. Enomoto
U.S. Department of the Interior

DAVID BERNHARDT, Acting Secretary

U.S. Geological Survey

James F. Reilly II, Director

U.S. Geological Survey, Reston, Virginia: 2019

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Suggested citation:

Trippi, M.H., Ryder, R.T., and Enomoto, C.B., 2019, Geologic cross section A–A′ through the Appalachian basin from the southern margin of the Ontario Lowlands 

province, Genesee County, western New York, to the Valley and Ridge province, Lycoming County, north-central Pennsylvania: U.S. Geological Survey Scientific 

Investigations Map 3425, 2 sheets, 74-p. pamphlet, https://doi.org/10.3133/sim3425.

ISSN 2329-1311 (print) 

ISSN 2329-132X (online)

ISBN 978-1-4113-4284-2
ii

Figures

[On map sheets]

1. Map showing the location of cross section A–A′ with political and geographic features in New York and Pennsylvania

2. Map showing the location of cross section A–A′ with surface and subsurface structural features in New York and Pennsylvania

3. Correlation chart of Proterozoic and Paleozoic rocks along cross section A–A′ in New York and Pennsylvania

Tables

Table 1. Drill holes used to construct cross section A–A’....................................................................................................................................................2

Contents

Introduction......................................................................................................................................................................................................................................1

Construction of the Cross Section ...............................................................................................................................................................................................1

Structural Framework ....................................................................................................................................................................................................................4

Basement Rocks and Associated Structures ...................................................................................................................................................................4

Thin-Skinned Structures.......................................................................................................................................................................................................6

Stratigraphic Framework...............................................................................................................................................................................................................7

Lower Cambrian to Upper Ordovician Siliciclastic and Carbonate Strata...................................................................................................................7

Upper Ordovician to Lower Silurian Siliciclastic Strata................................................................................................................................................10

Lower Silurian to Middle Devonian Carbonate and Evaporite Strata.........................................................................................................................11

Middle Devonian to Lower Mississippian Siliciclastic Strata......................................................................................................................................13

Middle and Upper Mississippian and Pennsylvanian Siliciclastic Strata..................................................................................................................15

Acknowledgments........................................................................................................................................................................................................................15

References Cited...........................................................................................................................................................................................................................15

Appendix 1. Table Summarizing Stratigraphic Units and Depths of Stratigraphic Units for Drill Holes 1–10 in Cross Section A–A′....................27

Appendix 2. Scale, Units, and Depths for Gamma-Ray Logging Runs..............................................................................................................................73
iii

Conversion Factors

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

meter (m) 3.281 foot (ft)

mile (mi) 1.609 kilometer (km)

kilometer (km) 0.6214 mile (mi)
Geologic Cross Section A–A′ Through the Appalachian Basin from the 

Southern Margin of the Ontario Lowlands Province, Genesee County, 

Western New York, to the Valley and Ridge Province, Lycoming County, 

North-Central Pennsylvania

By Michael H. Trippi, Robert T. Ryder, and Catherine B. Enomoto

Introduction

Geologic cross section A–A′ is the fifth in a series 

of cross sections constructed by the U.S. Geological 

Survey (USGS) to document and improve understanding of the geologic framework and petroleum systems 

of the Appalachian basin. Cross section A–A′ provides a 

regional view of the structural and stratigraphic framework of the Appalachian basin from the southern margin of the Ontario Lowlands province in western New 

York, across the Allegheny Plateau province of central 

New York and north-central Pennsylvania, to the Valley 

and Ridge province in north-central Pennsylvania, a distance of approximately 176 miles (mi) (figs. 1 and 2). 

This cross section is a companion to cross sections 

E–E′, D–D′, C–C′, and I–I′ (Ryder and others, 2008; 

Ryder and others, 2009; Ryder and others, 2012; Ryder 

and others, 2015) that are located approximately 100 to 

500 mi to the southwest (see index map, sheet 2). Cross 

section A–A′ complements earlier geologic or stratigraphic cross sections through the central New York 

and north-central Pennsylvania part of the Appalachian 

basin by Wagner (1966), Colton (1970), Faill and others 

(1977), Faill (1979), Berg and others (1980), Harper 

(1990), de Witt and others (1993), Hettinger (2001), 

Hickman and others (2006), Riley and others (2006), 

Smith and Leone (2010), and Mount (2014). Although 

some of these other cross sections show more structural 

and stratigraphic detail, they are of more limited extent 

geographically and stratigraphically.

Cross section A–A′ contains much information 

that is useful for evaluating energy resources in the 

Appalachian basin. Although the Appalachian basin 

petroleum systems identified by Swezey (2002) and 

Milici and others (2003) are not shown on the cross 

section, many of their key elements (such as source 

rocks, reservoir rocks, seals, and traps) can be inferred 

from lithologic units, unconformities, and geologic 

structures shown on the cross section. Other aspects 

of petroleum systems (such as the timing of petroleum 

generation and petroleum migration pathways) may be 

evaluated by burial history, thermal history, and fluid 

flow models on the basis of what is shown on the cross 

section. In addition, cross section A–A′ may be used 

as a reconnaissance tool to identify plausible geologic 

structures and strata for the subsurface storage of liquid 

waste (for example, Colton, 1961; Lloyd and Reid, 

1990; Clark and others, 2005) or for the sequestration 

of carbon dioxide (for example, Smith and others, 

2002; Lucier and others, 2006).

Construction of the Cross Section

Cross section A–A′ is oriented northwest to southeast, approximately normal to the structural grain of the 

region. Several abrupt bends in the section, however, 

are required to accommodate key drill holes that penetrate a thick section of Paleozoic sedimentary rocks.

Cross section A–A′ is based on geological and 

geophysical data from 10 deep drill holes (table 1), 

3 of which penetrate the Paleozoic sedimentary rocks 

of the basin and bottom in Mesoproterozoic crystalline basement rocks of the Grenville province (Rankin 

and others, 1993). The locations of the tops of each 

stratigraphic unit penetrated in the 10 deep drill holes 

were converted from depth in feet (ft) below the kelly 

bushing (KB) to depth below ground level (GL), and 

then were plotted on the cross section with respect to 

mean sea level (MSL). Detailed depth information for 

the tops of the stratigraphic units in each drill hole is 

reported in appendix 1.
2 Geologic Cross Section A–A′ Through the Appalachian Basin

Table 1. Drill holes used to construct cross section A–A’.

[Drill-hole locations are shown in figures 1 and 2. Source of all lithologic logs is Geological Sample Log Company (GSLC), Pittsburgh, Pa. Abbreviations are as follows: Co., County; Dept., Department; 

No., number; N.Y., New York; Pa., Pennsylvania]

Drillhole

number

Name used in text Location

American

Petroleum

Institute number

Latitude

(decimal

degrees)

Longitude

(decimal

degrees)

Lithologic

log

Cored intervals (in feet) and

stratigraphic unit

Total

depth

(in feet)

Age of oldest

rocks drilled

(stratigraphic unit)

New York

1 No. 1 J. Klotzbach Genesee Co., N.Y. (Akron 

7.5-minute quadrangle)

31–037–05117 43.040 -78.390 Yes Not available 3,950 Mesoproterozoic (granite 

and (or) gneiss)

2 No. 1 L. Tyler Genesee Co., N.Y. (Byron 

7.5-minute quadrangle)

31–037–04593 43.043 -78.077 Yes 3,520–3,546, Galway Formation 4,000 Mesoproterozoic (granite 

and (or) gneiss)

3 No. 1 Albert McClurg Livingston Co., N.Y. (Leicester 

7.5-minute quadrangle)

31–051–04552 42.835 -77.937 Yes Not cored 5,648 Mesoproterozoic (granite 

and (or) gneiss)

4 No. 1 Arthur N. Kennedy Livingston Co., N.Y. (Sonyea 

7.5-minute quadrangle)

31–051–04630 42.650 -77.756 Yes 5,660–5,690, Galway Formation 6,387 Middle Cambrian (Potsdam 

Sandstone)

5 No. 1 Hubbard Steuben Co., N.Y. (Avoca 

7.5-minute quadrangle)

31–101–21496 42.405 -77.463 No Not available 10,061 Middle Cambrian (Potsdam 

Sandstone)

6 No. 1 Robert Olin Steuben Co., N.Y. (Woodhull 

7.5-minute quadrangle)

31–101–03924 42.063 -77.430 Yes Not cored 13,508 Middle Cambrian (Potsdam 

Sandstone)

Pennsylvania

7 No. 1 Harry P. Dewey Tioga Co., Pa. (Marshlands 

7.5-minute quadrangle)

37–117–20057 41.689 -77.547 No Not available 15,082 Upper Cambrian (Gatesburg 

Formation)

8 No. 1 Pa. Dept. of Forest 

and Water Tract 129

Potter Co., Pa. (Tamarack 

7.5-minute quadrangle)

37–105–20182 41.489 -77.774 Yes Not cored 18,834 Middle Cambrian (Potsdam 

Sandstone)

9 No. 1 Pa. State Forest 

Tract 285–1

Clinton Co., Pa. (Glen Union 

7.5-minute quadrangle)

37–035–20276 41.371 -77.567 Yes 15,084–15,143, Black River Group;

15,883–15,943, Beekmantown Group;

17,620–17,650, Gatesburg Formation;

17,965–17,999, Gatesburg Formation

19,365 Middle Cambrian (Warrior 

Formation)

10 No. 1 W.E. Snyder Lycoming Co., Pa. (Linden 

7.5-minute quadrangle)

37–081–90002 41.142 -77.210 No Not available 5,808 Middle Cambrian (Warrior 

Formation)
Construction of the Cross Section 3

The correlation of stratigraphic intervals between 

drill holes was based on a variety of geophysical 

(wireline) and lithologic logs. The most commonly 

used geophysical logs were the gamma ray-neutron and 

gamma ray-density log suites, whereas the most commonly used lithologic logs were those produced by the 

Geological Sample Log Company (table 1). Gammaray logs used for correlations were digitized and (or) 

purchased as Log ASCII files (LAS), converted to 

graphic images, and then plotted next to their respective 

drill holes (appendix 2). The lithology assigned to each 

stratigraphic interval was simplified to just a few rock 

types and lithologic modifiers.

The data from the drill holes were supplemented 

by data about bedrock geology and topography. Some 

details of central New York stratigraphy were obtained 

from the geologic map of New York (Fisher and others, 

1970) and other bedrock geologic maps and reports by 

Clarke and Luther (1908), Luther (1911), Cooper and 

Williams (1935), Pepper and de Witt (1950, 1951), 

Pepper (1954), Pepper and others (1956), Colton 

(1956), de Witt (1956), Colton and de Witt (1958), 

de Witt and Colton (1959), Fisher (1959, 1977), Sutton 

and others (1962), Sutton (1963), Bergin (1964), and 

Rickard (1975). Similar details of the stratigraphy in 

north-central Pennsylvania were obtained from the 

geologic map of Pennsylvania (Berg and others, 1980) 

and bedrock geologic maps and reports by Colton 

(1963, 1967), Colton and Luft (1965), Wagner (1966), 

Faill and others (1977), and Faill (1979). Locations 

of numerous anticlines and synclines were obtained 

from the geologic maps of New York (Fisher and others, 1970) and Pennsylvania (Berg and others, 1980) 

and other previously published maps and reports by 

Cathcart (1932), Newland and Hartnagel (1932), Wedel 

(1932), Bradley and Pepper (1938), Bradley and others 

(1941), Prucha (1968), Frey (1973), Murphy (1981), 

Geiser (1988), and Harper (1990). Locations of numerous faults and lineaments were obtained from Van Tyne 

(1975), Fakundiny and Myers (1978), Isachsen (1985), 

Boyce and Morris (2002), Fakundiny and Pomeroy 

(2002), Jacobi (2002), Jacobi and Fountain (2002), 

Ouassaa and Forsyth (2002), Gold and others (2005), 

and Jacobi and Smith (2006).

The topographic profile for the cross section was 

created from the USGS National Elevation Dataset 

(NED) with a one arc-second cell size for parts of 

New York and Pennsylvania. This topographic profile 

is approximate and should not be used to determine 

accurate surface elevations. For example, we noticed 

errors near drill holes 8 and 9, where the actual surface 

elevation (as shown on well logs) is more than 100 feet 

above the topographic profile’s elevation. This discrepancy was probably due to the fact that the NED elevation values are average values for numerous points 

in the one arc-second cells. In locations with highly 

variable topography (as found near drill holes 8 and 9), 

the actual elevation of a point location within the cell 

may differ from the average elevation of the cell. The 

data can be accessed from the USGS NED website at 

https://nationalmap.gov/elevation.html.

Although some correlations shown on cross section A–A′ are based on our own interpretations, many 

correlations are adopted or modified from previous 

publications, and stratigraphic nomenclature follows 

existing terminology wherever possible. Useful references for stratigraphic correlations and (or) nomenclature include the following: Colton (1970), Berg and 

others (1980), Patchen and others (1985), Milici and 

de Witt (1988), and Swezey (2002) for the entire Paleozoic section; Riley and others (2006) for Cambrian and 

Ordovician rocks; Brett and others (1990) for Silurian 

rocks; de Witt and others (1993) for Devonian rocks; 

and Brezinski (1999) and Edmunds and others (1999) 

for Mississippian and Pennsylvanian rocks. A correlation chart for the stratigraphic units identified along 

cross section A–A′ is shown in figure 3.

Only selected unconformities are shown on cross 

section A–A′. Regional unconformities shown on cross 

section A–A′ and in figure 3 include (1) the basal Cambrian unconformity (see Read, 1989a), (2) the Middle 

Ordovician (Knox) unconformity (Mussman and others, 

1988), (3) the Upper Ordovician to lower Silurian 

(Cherokee) unconformity (Dennison and Head, 1975; 

Brett and others, 1990), (4) the Lower to Middle Devonian (Wallbridge) unconformity (Dennison and Head, 

1975), (5) the Upper Devonian unconformity (de Witt 

and others, 1993), (6) the Middle Mississippian unconformity (modified from Brezinski, 1999), and (7) the 

Lower Pennsylvanian unconformity (Edmunds and others, 1999). The correlation of these unconformities with 

North American sequences of Sloss (1988) is shown on 

figure 3 and shown by Ettensohn (1994) and Swezey 

(2002).

The locations of most basement-involved faults 

along cross section A–A′ are based on features described 

by Rickard (1973), Van Tyne (1975), Fakundiny and 

Myers (1978), Beardsley and Cable (1983), Henderson 

and Timm (1985), Harper (1989), Shumaker and Wilson 

(1996), Fakundiny and Pomeroy (2002), Jacobi (2002), 

Jacobi and Fountain (2002), Ouassaa and Forsyth 

(2002), Jacobi and Smith (2006), and Smith (2006). 

We also locate a basement fault just north of drill hole 

7 based on discussions with J.S. Hnat of Shell Oil (oral 

commun., 2015).

Prominent thin-skinned structures (Rodgers, 

1963) defined by large-scale thrust faults with basal 

detachment in lower Paleozoic strata and associated 

ramp anticlines are located at the southeastern end of 

cross section A–A′ near drill hole 10. These structures, 

characteristic of the Valley and Ridge province (fig. 1) 

are juxtaposed against lesser deformed strata of the 

Allegheny Plateau (fig. 1) to form the Allegheny 

structural front (Rodgers, 1970; Faill, 1998; Faill and 

Nickelsen, 1999) (figs. 1 and 2).

The Allegheny structural front was located by Faill 

and others (1977) about 8 mi northwest of drill hole 10. 

Although thin-skinned structures continue northwest 

of the Allegheny structural front into the Allegheny 

Plateau of Pennsylvania and New York, they consist of 

folds with lower amplitudes (such as those shown on 

geologic maps of Cathcart, 1932; Wedel, 1932; Colton, 

1963, 1967; Colton and Luft, 1965; Fisher and others, 
4 Geologic Cross Section A–A′ Through the Appalachian Basin

1970; Berg and others, 1980; and on fig. 2) and thrust 

faults with smaller offsets and younger detachment 

zones. Moreover, all basement-involved faults identified on cross section A–A′ are located in the Allegheny 

Plateau and the Ontario Lowlands (fig. 1).

Structural Framework

Basement Rocks and Associated 

Structures

Basement rocks along cross section A–A′ consist 

of igneous and metamorphic rocks of the subsurface 

extension of the Grenville province (Rankin and others, 

1993). Most isotopic ages of these Grenville province 

rocks range between 1,350 to 950 million years before 

present (Ma, or mega-annum), and many ages cluster 

around 1,100 to 1,000 Ma (Rankin and others, 1993) 

(fig. 3).

Typical of many foreland basins, the crystalline 

basement of the Appalachians is a homoclinal ramp 

that dips gently from an interior craton to the external 

margin of a fold-and-thrust belt. Along cross section 

A–A′, this basement ramp deepens progressively southeastward from about 3,000 ft below mean sea level 

(MSL) near drill hole 1, to about 26,000 ft below MSL 

beneath the White Deer syncline near drill hole 10. This 

gradual southeastward deepening of the basement ramp 

along cross section A–A′ is interrupted by the Rome 

trough (fig. 2), a Middle Cambrian rift system that runs 

southwest to northeast from central Kentucky through 

West Virginia and Pennsylvania and possibly into 

south-central New York (Beardsley and Cable, 1983; 

Harper, 1989; Shumaker and Wilson, 1996; Harris and 

others, 2004; Jacobi and Smith, 2006). The northwestern limit of the Rome trough on cross section A–A′ is 

shown as the down-to-the-southeast basement-involved 

fault located 1 mi northwest of drill hole 6, whereas the 

southeastern limit of the Rome trough on cross section 

A–A′ is shown as the down-to-the-northwest basementinvolved fault located 1 mi northwest of drill hole 9 

(fig. 2). Along cross section A–A′, the Rome trough is 

about 44 mi wide and has a structural relief on the top 

of basement that ranges from about 100 to 300 ft at 

its northwestern margin to an estimated 3,800 ft at 

its deepest location southeast of drill hole 7. The 

northwest-boundary fault of the Rome trough as recognized in this report was defined by seismic data shown 

by Beardsley and Cable (1983) and its location was 

later corroborated by M.S. Cable, University of South 

Carolina (written commun., 1990). Harper (1989) and 

Jacobi (2002) also showed this fault just northwest of 

drill hole 6. The upthrown northwestern side of this 

basement-involved fault marks the Kane arch of Ryder 

(1992) (following the Kane gravity high of Diment and 

others (1980)). The southeast-boundary fault of the 

Rome trough as recognized by this report was defined 

by seismic data shown in Henderson and Timm (1985) 

just northwest of drill hole 9; however, Harper (1989) 

and Jacobi (2002) place the southeast-boundary fault of 

the Rome trough (with its northwest side downthrown) 

to the southeast of drill hole 9, but we show that fault 

with the southeast side downthrown as described by 

Shumaker and Wilson (1996), resulting in an uplifted 

horst block between this fault and the fault described by 

Henderson and Timm (1985).

On the basis of seismic data and data from an 

offsetting drill hole in the footwall, Shell Oil staff (J.S. 

Hnat, Shell Oil, written commun., 2015) propose a 

major down-to-the-southeast basement-involved fault 

located less than a mile northwest of drill hole 7 in 

Tioga County, Pennsylvania. This fault has been interpreted as a syndepositional normal fault active during 

an extension phase in the Appalachian basin from Neoproterozoic until Late Ordovician, resulting in a thickening of the formations below the Reedsville Shale on 

the southeastern side of the fault. Starting in the Late 

Ordovician, there was little to no fault movement, as 

shown by uniform thickness of formations on opposite 

sides of the fault from the Reedsville Shale up through 

the Bloomsburg Formation. Reactivation and reverse 

fault movement took place during a compression phase 

in the late Silurian, resulting in uplift of the formations 

above the Utica (Antes) Shale on the southeast side of 

the fault (J.S. Hnat, Shell Oil, written commun., 2015).

Three faults shown by Shumaker and Wilson 

(1996) are not recognized in this report. The first fault 

is about 3 mi northwest of drill hole 8, the second is 

6 mi northwest of drill hole 10, and the third is 2 mi 

southeast of drill hole 10.

The Rome trough that intersects cross section 

A–A′ is a smaller structural feature (with less structural 

relief on basement) than the trough in Kentucky (Harris and others, 2004), West Virginia (Shumaker and 

Wilson, 1996), and southern Pennsylvania (Kulander 

and Ryder, 2005), but its northward trend beyond cross 

section A–A′ remains uncertain. The question remains 

whether the Rome trough continues its northeastward 

trend into New York as interpreted by Harper (1989) 

and Jacobi (2002) or changes to an east-northeast trend 

and remains largely in Pennsylvania as interpreted by 

Shumaker and Wilson (1996), Faill (1997a), Repetski 

and others (2008), and Ryder and others (2012).

Harper (1989) proposed that the Rome trough has 

been displaced along several cross-structural discontinuities (CSDs), including the Lawrenceville-Attica 

lineament in Steuben County, New York. Jacobi (2002) 

shows about 18 mi of right-lateral movement of the 

Rome trough’s northwest-boundary fault along the 

Lawrenceville-Attica lineament (fig. 2). Similar lateral 

displacement of the southeast-boundary fault of the 

Rome trough along the Lawrenceville-Attica lineament 

is also shown in Tioga, Lycoming, and Bradford Counties, Pennsylvania.

Many normal (extensional) basement faults in 

New York and Pennsylvania were reactivated at least 

once during the Paleozoic to produce either renewed 

subsidence or small-scale inversion (Fakundiny and 
Structural Framework 5

Myers, 1978; Fakundiny and Pomeroy, 2002; Jacobi, 

2002; Jacobi and Fountain, 2002; Ouassaa and Forsyth, 

2002; Gold and others, 2005; and Jacobi and Smith, 

2006). Small-scale inversion on these faults probably 

resulted from contraction during the Late Mississippian 

to Permian Alleghanian orogeny. At least 12 basement 

faults in New York discussed by Jacobi (2002) intersect 

cross section A–A′ including the following (listed from 

northwest to southeast): (1) an unnamed northwesttrending fault in eastern Genesee County; (2) the western, central, and eastern faults of the Clarendon-Linden 

fault system (CLFS); (3) the Leroy fault; (4) the Retsof 

fault; (5) two unnamed east-trending faults in northwestern Steuben County; (6) the Bolivar fault system; 

(7) the Keuka Lake splay fault; (8) the LawrencevilleAttica lineament; and (9) the Rome trough northwestboundary fault.

The unnamed northwest-trending fault in eastern 

Genesee County may be related to the northweststriking Attica-Lockport and Folsomdale faults 13 to 

23 mi to the south, respectively, and the similarly 

oriented Georgian Bay linear zone (fig. 2) in Niagara 

County (Jacobi, 2002). R.D. Jacobi (written commun., 

2016) suggested that this unnamed fault may extend 

from basement to the surface with negligible vertical 

movement above the Trenton Group with up to 20 ft of 

vertical displacement below the Trenton Group.

The most studied fault system in western New 

York is the CLFS (Van Tyne, 1975; Fakundiny and 

Pomeroy, 2002; Jacobi, 2002; Jacobi and Fountain, 

2002; Jacobi and Smith, 2006), which includes three 

parallel north-striking faults that extend from Lake 

Ontario in northwestern Monroe County through 

Genesee and Wyoming Counties into northwestern 

Allegany County, and one southwest-striking branch 

off of the western fault in Genesee, Wyoming, and Erie 

Counties. Fakundiny and Pomeroy (2002) interpret 

normal movement for all three main CLFS faults with 

the western side down. They describe the central CLFS 

as a broad zone (up to 1.24 mi wide) of complexly 

fractured strata instead of a single fault (Fakundiny and 

Pomeroy, 2002). They interpret 164 to 328 ft of vertical 

displacement at the top of the Trenton Group, whereas 

the top of basement shows offset in some locations and 

none in others (Fakundiny and Pomeroy, 2002). They 

show no offset of the top of the Onondaga Limestone 

along these faults (Fakundiny and Pomeroy, 2002). Van 

Tyne (1975) interprets the sense and amount of vertical displacement for the CLFS faults differently. On 

his C‒D cross section (located about 5 miles north of 

cross section A–A′) he shows the western fault to be 

down-to-the-east with approximately 25 ft of vertical 

displacement (as judged by offset of the tops of the 

Medina Group and Trenton Group). The central fault is 

interpreted as down-to-the-west with the amount of vertical displacement varying from about 75 ft (at the top 

of the Trenton Group) to about 100 ft (at the top of the 

Medina Group). The eastern fault is shown as down-tothe-east with vertical displacement varying from 25 ft 

(at the top of the Medina Group) to 50 ft (at the top 

of the Trenton Group). We used VanTyne’s C‒D cross 

section as a model for our configuration of the three 

CLFS faults on cross section A–A′. South of the cross 

section in Allegany County, the Onondaga and Tully 

Limestones have up to 120 ft of total offset (for all three 

faults) with the western side down (Jacobi and Fountain, 1996; Jacobi, 2002). Cross section A–A′ intersects 

the three main CLFS faults between 0 and 5 mi west of 

drill hole 2 in Genesee County, New York. Fakundiny 

and Pomeroy (2002) and Ouassaa and Forsyth (2002) 

indicate that the CLFS is probably the surface expression of the boundary zone between two deep supercrustal basement megablocks: the Frontenac terrane 

to the east, and the Elzevir terrane to the west. Jacobi 

(2002) described varying amounts and directions of slip 

on these faults at different locations in Allegany County, 

but all of them appear to have been initiated due to 

Iapetan rifting activity (late Neoproterozoic [Ediacaran] 

to Early Cambrian) and also show movement during the 

Taconic orogeny (Ordovician to early Silurian).

The north-striking Leroy and Retsof faults pass 

through Monroe, Genesee, Livingston, and Wyoming 

Counties (Jacobi, 2002). The Leroy fault, which intersects cross section A–A′ between drill holes 2 and 3, 

may be an Ordovician growth fault downthrown to the 

east; the fault may also affect basement rocks similar to 

the CLFS faults to the west. The Leroy fault may have 

up to 75 ft of vertical displacement below the Utica 

Shale (R.D. Jacobi, written commun., 2016). Also, 

fracture swarms may indicate that the fault extends all 

the way to the surface (R.D. Jacobi, written commun., 

2016). The Retsof fault, which intersects cross section 

A–A′ near drill hole 3, is inferred from north-striking 

fractures, faults, and stream and slope lineaments in 

a north-striking valley near the towns of Retsof and 

Greigsville, New York (fig. 1). Jacobi (2002) suggests 

that the Retsof fault may actually be a 5-mi-wide zone 

of faulting that extends from a north-striking valley 

near the towns of Retsof and Griegsville north to Lake 

Ontario. R.D. Jacobi (written commun., 2016) indicated 

that the amount of vertical displacement may be up to 

40 ft downthrown to the northwest.

In northern Steuben County between drill holes 

4 and 5 there are two unnamed, parallel east-striking 

faults that may be western extensions of the Glodes 

Corners Road graben faults (Columbia Natural 

Resources, Inc., 2000; Jacobi, 2002; Smith, 2006) and 

Muck Farm graben faults, between 10 and 20 miles 

east of cross section A–A′. The Glodes Corners Road 

graben faults are believed to have been active from 

the latest Neoproterozoic (Ediacaran) through the 

Cambrian, but are not parallel to the northeast-striking 

Rome trough faults to the south; therefore, it is unclear 

if they are related to the opening of the Rome trough or 

if they formed independently of that structure (Jacobi, 

2002). Reactivation of the faults during the Ordovician resulted in localized dolomitization of the Black 

River and lower Trenton Group limestones, creation 

of a graben, and increasing porosity that made conditions favorable for gas accumulation (Columbia Natural 
6 Geologic Cross Section A–A′ Through the Appalachian Basin

Resources, Inc., 2000; Patchen and others, 2006; 

Smith, 2006). Smith (2006) believes these faults to 

be the upward extension of a basement-rooted flower 

structure.

The Bolivar fault system (Jacobi, 2002), included 

in the following thin-skinned structures section, may 

possibly be associated with older basement faults that 

have been reactivated (R.D. Jacobi, oral commun., 

2016). The amount of vertical displacement and vertical 

extent are unknown.

The Keuka Lake fault splay of Jacobi (2002) intersects the cross section between drill holes 5 and 6. It 

trends to the northeast and intersects cross section A–A′

at an angle of about 30 degrees. Magnetic gradient data 

indicates that the Keuka Lake fault splay may affect 

basement rocks (Jacobi, 2002). Although we indicate 

the location of the Keuka Lake fault splay on A–A′, we 

do not show it as a fault because its amount of dip slip 

and vertical extent were unspecified by Jacobi (2002).

The Lawrenceville-Attica lineament that intersects cross section A–A′ between drill holes 5 and 6 in 

Steuben County is interpreted to be the southeastern 

extension of the Attica-Lockport and Folsomdale faults 

of Erie, Genesee, and Wyoming Counties and may be 

a strike-slip fault with right-lateral movement that 

offsets the Rome trough’s northwest-boundary fault by 

about 18 mi (Jacobi, 2002). The Lawrenceville-Attica 

lineament may also exhibit normal movement with 

the southwestern side down, as shown by a monocline 

with 492 ft of movement at the top of the Onondaga 

Limestone (Jacobi, 2002). Several other authors 

(Diment and others, 1980; Gold and Pohn, 1985; 

Harper, 1989; Boyce and Morris, 2002) have shown the 

Lawrenceville-Attica lineament as a cross-structural 

discontinuity (CSD) with possible strike-slip and (or) 

normal movement. On cross section A–A′ we indicated 

the location of the Lawrenceville-Attica lineament, but 

did not show it as a fault or monocline because the area 

was already extremely complex with two anticlinesyncline pairs superimposed on the regional dip.

Thin-Skinned Structures

Typical Appalachian thin-skinned structures 

(bedding-plane detachment zones, footwall ramps, 

ramp anticlines, and imbricate thrust faults) are contractional in origin and probably developed during the 

Late Mississippian to Permian continental collision 

(Alleghanian orogeny) between eastern North America 

and Africa (Rodgers, 1970; Rodgers, 1988; Hatcher 

and others, 1989; Faill, 1998). Crustal contraction that 

accompanied this collision caused large horizontal 

displacements of thick, competent panels of Paleozoic 

strata along thin, incompetent Paleozoic strata surfaces. 

In places, compression from the late Silurian through 

the Alleghanian orogeny reactivated basement faults 

and locally inverted the Rome trough (Harris, 1978; 

Shumaker and Wilson, 1996; Hickman and others, 

2006; J.S. Hnat, Shell Oil, written commun., 2015).

Thin-skinned structures in the Valley and Ridge 

province are dominated by a system of foreland-vergent 

thrust faults (terminology from McClay, 1992) that 

include the Jersey Shore and Antes thrust faults, an 

unnamed thrust fault below the Nippenose anticline 

and White Deer syncline, and a sub-horizontal detachment zone (décollement) at the base of the Silurian 

Salina Group (Faill and others, 1977). From its junction 

with the Jersey Shore fault, the basal detachment zone 

extends northwestward into New York to at least as 

far as drill hole 4. In addition, minor sub-horizontal 

detachment zones in the Ordovician Utica (Antes) 

Shale and Cambrian Waynesboro Formation are 

interpreted beneath the Allegheny structural front. The 

unnamed thrust fault below the Nippenose anticline 

and White Deer syncline and the associated sub-Salina 

detachment zone were probably the first to form when 

a thick panel of Cambrian to Devonian (or younger) 

rocks was decoupled from underlying strata and was 

thrust northwestward up a major tectonic (footwall) 

ramp. This ramp connected the basal zone of detachment (footwall flat) in the Cambrian Waynesboro 

Formation to the upper zone of detachment (hangingwall flat) at the base of the Silurian Salina Group in 

Pennsylvania and New York (Scanlin and Engelder, 

2003) (upper and lower level décollement of Harris and 

Milici, 1977; thrust terminology from McClay, 1992). 

At some later time, the Antes thrust fault probably 

grew as a splay off the top of the unnamed thrust fault, 

thereby allowing the fault block above the splay to ride 

upward rather than travelling to the northwest along the 

basal Salina detachment zone. Either synchronous with 

the Antes thrust fault or slightly later, the Jersey Shore 

fault developed as a forward-breaking imbricate fault 

block with a lower detachment zone in the Waynesboro 

Formation and a southeastward-dipping ramp. This 

ramp cut upsection through strata at least as young as 

Early Devonian and, in turn, offset the unnamed thrust 

fault by several thousand feet.

The upper detachment zone extends northwest 

from the Jersey Shore ramp perhaps for more than 

100 mi along the base of the Salina Group before it 

ends at or near drill hole 4. Multiple anticlines, synclines, and imbricate splay faults formed above this 

detachment surface as a result of Alleghanian compression. Locations of numerous anticlines and synclines 

were obtained from the geologic maps of New York 

(Fisher and others, 1970) and Pennsylvania (Berg and 

others, 1980) and other previously published maps and 

reports by Cathcart (1932), Newland and Hartnagel 

(1932), Wedel (1932), Bradley and Pepper (1938), 

Bradley and others (1941), Prucha (1968), Frey (1973), 

Murphy (1981), Geiser (1988), and Harper (1990). 

Splay faults shown on the cross section were located 

beneath anticlines. A series of faults similar to these 

have been interpreted in seismic sections near the crests 

of folds in this area (J.S. Hnat, Shell Oil, written commun., 2015).

The Bolivar fault system described by Jacobi 

(2002) is shown as a northeast-striking fault in Steuben 

and Allegany Counties, New York (fig. 2). The fault 

intersects cross section A–A′ about 6 miles southeast of 
Stratigraphic Framework 7

drill hole 5. This fault may be a splay rising from the 

Salina Group detachment zone, but it is possible that 

it may be associated with an older basement faults that 

have been reactivated. Numerous possible northeastoriented faults between drill holes 3 and 6 (lineaments 

and “lineament bundles” of Jacobi (2002)) are shown 

as dashed lines and green and pink polygons in figure 2 

(green polygons are from Jacobi (2002); pink polygons 

are from R.D. Jacobi, written commun., 2016). The 

northeast-strike of these features may indicate that 

they are related to the similarly oriented folds and 

faults in the Allegheny Plateau created by Alleghanian 

contraction.

Stratigraphic Framework

The sedimentary rocks shown on cross section 

A–A′ span most of the Paleozoic Era, and their thickness ranges from about 4,000 ft at drill hole 1 to about 

27,000 ft at the Allegheny structural front at drill hole 

10. Lithology, nomenclature, and depositional and 

tectonic settings of the sedimentary rocks along cross 

section A–A′ are briefly outlined and discussed in the 

following text. A more detailed treatment is available in 

regional geological summaries by Colton (1970), Milici 

and de Witt (1988), Read (1989a), and Faill (1997a, b, 

1998).

Much of the eastward thickening of strata in the 

Appalachian basin was caused by regional tectonism. 

During the Neoproterozoic (Ediacaran) to Early Cambrian, as the proto-Atlantic (Iapetus) Ocean opened 

and formed a rifted continental margin, cooling and 

thermal contraction of the lithosphere caused subsidence, which provided accommodation or preservation 

space for sediments to build an eastward-facing passive 

continental margin (Bond and others, 1988; Read, 

1989a). During several later periods in the Paleozoic, 

subsidence caused by thrust loading during various 

orogenic events provided additional accommodation 

or preservation space for sediments to accumulate in 

Appalachian foreland basins (Quinlan and Beaumont, 

1984). Eustatic changes also played a role in the 

eastward thickening of Appalachian strata (Bond and 

others, 1988). For example, a rise in sea level can 

cause load-induced subsidence (by sediments and the 

overlying water column) and provide accommodation 

space for additional sediments on the outer continental 

shelf, whereas a fall in sea level can cause erosion of 

the inner continental shelf. These eustatic changes were 

caused by changes in global climate and (or) changes in 

global tectonic activity.

Lower Cambrian to Upper Ordovician 

Siliciclastic and Carbonate Strata

Lower Cambrian to Upper Ordovician siliciclastic and carbonate strata are characterized by dolomite, 

limestone, and lesser amounts of gray shale, red shale, 

and sandstone (fig. 3). Along cross section A–A′, these 

strata thin dramatically from a thickness of about 

11,000 feet beneath the Allegheny structural front in 

central Pennsylvania to about 3,000 ft in west-central 

New York. Well 9 penetrates about 8,100 ft of Lower 

Cambrian to Upper Ordovician strata. In the eastern 

part of cross section A–A′ (Allegheny Plateau and Valley and Ridge provinces in north-central Pennsylvania), 

the Lower Cambrian to Upper Ordovician siliciclastic 

and carbonate strata consist of the following units (in 

ascending order): the Antietam Formation (and the 

equivalent Potsdam Sandstone), Tomstown Formation, 

Waynesboro Formation, Pleasant Hill Formation, Warrior Formation, Gatesburg Formation, Beekmantown 

Group (including the Larke, Stonehenge, Nittany, Axemann, and Bellefonte Formations), Black River Group, 

and Trenton Group (fig. 3). The equivalent Cambrian 

to Upper Ordovician strata of south-central New York 

consist of the following units (in ascending order): 

Potsdam Sandstone, Galway Formation, Little Falls 

Dolomite, Tribes Hill Dolomite, Bellefonte Formation, 

Black River Group, and Trenton Group (fig. 3).

The distribution and lithology of Cambrian rocks 

in the southeastern part of cross section A–A′ are very 

speculative because deep drill holes are largely absent. 

Lithology and thickness data for Cambrian rocks in 

this area are limited to (1) drill holes 9 and 10, where 

the upper part of the Warrior Formation is penetrated; 

(2) drill hole 8, where the upper part of the Potsdam 

Sandstone is penetrated; and (3) drill hole 7, where the 

upper sandy member of the Gatesburg Formation is 

penetrated. Cambrian units between the western boundary of the Rome trough and the northwestern end of 

cross section A–A′ are reasonably well documented by 

drill holes 1 through 6.

The Lower Cambrian Antietam Formation, the 

Lower Cambrian Tomstown Formation, the Lower and 

Middle Cambrian Waynesboro Formation, and the Middle Cambrian Pleasant Hill Formation are the oldest 

stratigraphic units shown on cross section A–A′. These 

units have been projected into the southeastern end of 

the cross section from known localities 100 mi or more 

to the south in south-central Pennsylvania (Butts, 1945; 

Wilson, 1952; Root, 1968; Ryder and others, 2012) and 

west-central Maryland (Brezinski, 1992). Although 

Wagner (1966) recognized the Pleasant Hill Formation 

in drill hole 10, this unit has been reinterpreted in this 

study as the Middle Cambrian Warrior Formation. The 

Antietam, Tomstown, Waynesboro, and Pleasant Hill 

Formations have an estimated combined thickness of as 

much as 2,200 ft beneath the Allegheny structural front.

The Lower Cambrian Antietam Formation is a 

basal Cambrian sandstone that rests unconformably on 

Mesoproterozoic and Neoproterozoic basement rocks 

of the Grenville province. The Antietam Formation is 

interpreted as a transgressive marine deposit with a sediment source to the west and northwest. The Antietam 

Formation is overlain conformably by predominantly 

dolomite beds of the Lower Cambrian Tomstown Formation. Carbonate strata of the Tomstown Formation 
8 Geologic Cross Section A–A′ Through the Appalachian Basin

are interpreted as transgressive marine deposits that 

accumulated on a marine shelf and carbonate ramp 

after the adjacent craton was submerged by the Iapetus 

Ocean (Read, 1989a, b).

The Waynesboro Formation in cross section A–A′

rests conformably on the Tomstown Formation and 

probably consists of clastic red beds, dolomite, sandstone, and green and gray shale judging from subsurface and outcrop studies in south-central Pennsylvania 

(Root, 1968; Ryder and others, 2012) and west-central 

Maryland (Brezinski, 1992). Although an Early Cambrian age is commonly cited for the Waynesboro Formation (Butts, 1945; Palmer, 1971; Brezinski, 1992), fossil evidence is very sparse and a Middle Cambrian age 

is possible for the upper part of the formation (Stose, 

1909; Root, 1968; Read 1989a, b); thus, an Early and 

Middle Cambrian age is assigned to the Waynesboro 

Formation in this report. The Waynesboro Formation is 

interpreted as a shallow-water nearshore marine deposit 

(Woodward, 1949; Brezinski, 1992).

The Pleasant Hill Formation is predominantly a 

limestone unit that rests conformably on the Waynesboro Formation. The Middle Cambrian age of the 

Pleasant Hill Formation is based on trilobite fauna 

(Wilson, 1952). This limestone probably was deposited 

in a shallow-marine setting.

Approximately 10 mi southeast of drill hole 9, the 

Tomstown, Waynesboro, and Pleasant Hill Formations 

are interpreted to pinch out northwestward (as indicated 

by a facies change) into the 1,000- to 1,200-ft-thick 

Middle to Upper Cambrian Potsdam Sandstone. Also 

at this locality, the Antietam Formation merges with 

the lower part of the Potsdam Sandstone, another 

basal Cambrian sandstone. The Potsdam Sandstone 

extends across most of cross section A–A′ from near 

drill hole 9 to between drill holes 2 and 3. In the Rome 

trough, between the southeast-boundary fault of the 

trough (Henderson and Timm, 1985) and the unnamed 

reactivated basement fault just northwest of drill hole 7 

(J.S. Hnat, Shell Oil, oral commun., 2015), the Potsdam Sandstone is interpreted to thicken to as much as 

2,800 ft and intertongue with the Middle and Upper 

Cambrian Warrior Formation. Between the unnamed 

reactivated basement fault and the northwest-boundary 

fault of the Rome trough (Beardsley and Cable, 1983), 

the Potsdam Sandstone thickens slightly from about 

450 ft to about 500 ft. Northwest of the northwestboundary fault, the Potsdam Sandstone thins gradually 

from about 500 ft to a pinch-out edge between drill 

holes 2 and 3.

The Middle and Upper Cambrian (based on trilobite fauna; Wilson, 1952) Warrior Formation near drill 

hole 10 is about 2,400 ft thick and consists primarily of 

sandy dolomite with two limestone units in the upper 

900 ft. Wagner (1966) identified the lower limestone in 

drill hole 10 as the Pleasant Hill Formation, but in this 

study the lower limestone is reassigned to the Warrior 

Formation. The additional undrilled part of the Warrior 

Formation below drill hole 10 is considered to be 600 ft 

of sandy dolomite, thus suggesting a total thickness of 

3,000 ft for the Warrior Formation in this locality. 

About 10 mi southeast of drill hole 9, the Warrior 

Formation thickens to about 3,300 ft. In and below drill 

hole 9, the Warrior Formation thins to about 2,300 ft 

thick above a horst block adjacent to the southeastboundary normal basement fault of the Rome trough. 

The drilled 800 ft of the Warrior Formation in drill 

hole 9 consists of (in ascending order) sandy dolomite, 

sandstone, and black shale that appears to replace (by 

facies change) the limestone and thin dolomite beds 

of the upper part of the Warrior Formation found in 

drill hole 10. The undrilled 1,500 ft of proposed sandy 

dolomite below drill hole 9 is roughly equivalent to the 

estimated 2,000-ft thickness of the lower sandy dolomite in drill hole 10. Drill hole 8 penetrates a complete 

1,000-ft-thick interval of the Warrior Formation that 

consists of (in ascending order) sandy dolomite, sandstone, black shale, and more dolomite. The interpreted 

abrupt northwestward thinning of the Warrior Formation between drill holes 8 and 9 resulted mainly from 

interfingering and overstepping the underlying Potsdam 

Sandstone. Between drill holes 7 and 8 the shale unit 

grades into a dolomite, whereas the upper dolomite and 

middle sandstone units remain the same. The Warrior 

Formation continues to thin northwestward beyond the 

Rome trough to the New York border where it is called 

the following members of the lower Galway Formation (in ascending order): (1) the C sandstone, (2) the 

B interbedded sandstone and dolomite, and (3) the B 

dolomite (modified from Smith, 2012).

Complete sections of the Upper Cambrian Gatesburg Formation were penetrated in drill holes 8 through 

10, and the upper half of the formation was penetrated 

in drill hole 7. The Gatesburg Formation includes the 

following members (in ascending order): (1) the lower 

sandy member, which is a dolomitic quartzarenite sandstone; (2) the Ore Hill Member, which is a limestone 

with dolomite interbeds (in drill holes 9 and 10) grading into a limy dolomite (in drill holes 7 and 8); (3) the 

upper sandy member, which is a dolomitic quartzarenite sandstone; and (4) the Mines Dolomite Member, 

which is a chert-bearing dolomite. These members of 

the Gatesburg Formation are consistent with the members reported in outcrops (Wilson, 1952), except for the 

Stacy Dolomite Member (Wilson, 1952) at the base of 

the Gatesburg Formation, which is unrecognizable and 

has been combined with the lower sandy member.

The Upper Cambrian age of the Gatesburg 

Formation is based on trilobite fauna in the Ore Hill 

Member (Wilson, 1952). The sandy members of the 

Gatesburg Formation are interpreted as shallow-marine 

and peritidal deposits (Wilson, 1952; Riley and others, 

1993). Moreover, the quartzarenite composition of the 

sandstone units suggests that they were derived from 

the craton (Riley and others, 1993). The Gatesburg 

Formation continues northwest to the New York border 

where the name changes to the Little Falls Dolomite 

and the upper Galway Formation of New York. The 

Mines Dolomite Member of the Gatesburg Formation 

is equivalent to the Little Falls Dolomite, whereas the 

upper sandy member, Ore Hill Member, and lower 

sandy member of the Gatesburg Formation are equivalent, respectively, to the A sandstone; the A interbedded 
Stratigraphic Framework 9

sandstone and dolomite, and A dolomite (undivided); 

and the B sandstone members of the Galway Formation 

(Smith, 2012). The Galway Formation and Little Falls 

Dolomite both become thinner to the northwest where 

erosion that produced the Knox unconformity removed 

the Little Falls Dolomite between drill holes 3 and 4 

and the upper sandstone member of the Galway Formation between drill holes 2 and 3. Two miles northwest 

of drill hole 6, we chose to combine the members of the 

Galway Formation below the upper sandstone member 

into one undivided unit. One unnamed thin sandstone 

member in the Galway Formation is shown at drill 

hole 3, and two more unnamed thin sandstone members 

are shown at drill hole 1. Please note that in some cases 

(as described above) we have chosen not to represent 

the separate members of a formation on the cross section or correlation chart (fig. 3). This does not necessarily indicate that the identification of the members is 

impossible in the field. We may still discuss the separate members in this report and (or) list elevations for 

the separate members in appendix A. In some locations, 

we have also chosen to represent multiple formations as 

one undivided unit. In these locations, we labelled the 

units with a list of the formations included, followed by 

“(undivided)” (for example, “Shriver Chert, Mandata 

Shale, Corriganville Limestone, New Creek Limestone 

(undivided)”). We still discuss these formations separately in the text and list the formation top elevations 

separately in appendix A.

The Lower and Middle Ordovician Beekmantown 

Group consists of dolomite and limestone formations 

(Wagner, 1966). The Beekmantown Group is about 

3,000 ft thick in the Valley and Ridge province (drill 

hole 10) and beneath the adjoining Allegheny structural front where it consists (in ascending order) of the 

following formations: Larke Formation (dolomite), 

Stonehenge Formation (limestone), Nittany Formation 

(dolomite), Axemann Formation (primarily limestone), 

and Bellefonte Formation (primarily dolomite) (Wagner, 1966). Farther to the northwest, on the southeast 

flank of the Rome trough, drill hole 9 penetrated about 

1,600 ft of the Beekmantown Group, where two intraformational unconformities are recognized by Wagner 

(1966). These two unconformities are probably separate 

tongues of the regional Middle Ordovician Knox 

unconformity that extend into central Pennsylvania. 

The lower unconformity (Wagner, 1966) marks the top 

of the Larke Formation and the Stonehenge Formation. 

Following Wagner (1966), the Stonehenge Formation is 

removed by erosion associated with the lower unconformity between drill holes 9 and 10, and the overlying 

Nittany and Axemann Formations pinch out northwestward by onlap against the lower unconformity. The 

upper unconformity within the Beekmantown Group 

in drill hole 9 is located near the top of the Bellefonte 

Formation. The upper unconformity disappears southeastward of drill hole 9 so that the contact between 

the lower and upper parts of the Bellefonte Formation 

becomes gradually conformable (Wagner, 1966; Harris 

and Repetski, 1982) toward the Allegheny structural 

front and the Valley and Ridge province.

On the Kane arch (northwest of the fault near drill 

hole 6) on the northwest flank of the Rome trough, 

Beekmantown Group-equivalent strata (Tribes Hill 

Dolomite and the overlying Bellefonte Formation) thin 

to about 500 ft. Between drill hole 9 and the northern 

end of cross section A–A′, erosion associated with the 

Knox unconformity removes progressively downsection the following intervals: (1) the Bellefonte Formation (lower part) (between drill holes 6 and 7), (2) the 

Larke Formation-equivalent Tribes Hill Dolomite 

(between drill holes 5 and 6), (3) the Little Falls Dolomite (between drill holes 3 and 4), and (4) the upper 

sandstone member of the Galway Formation (between 

drill holes 2 and 3). The Bellefonte Formation (upper 

part) pinches out between drill holes 5 and 6 by onlap.

The Galway Formation, Little Falls Dolomite, 

and Bellefonte Formation are overlain by a widespread 

Middle to Upper Ordovician limestone-dominated 

interval that extends across nearly the entire cross section. This limestone interval varies in thickness from 

about 1,400 ft in the southeast portion of the Allegheny 

Plateau (drill hole 9) to about 900 ft in western New 

York (drill hole 1). On the basis of the nomenclature 

used in the outcrop belt of central Pennsylvania 

(Thompson, 1963; Rones, 1969; Laughrey and others, 

2003) and in the subsurface near drill hole 10 (Wagner, 

1966), the limestone interval is divided into (in ascending order) the Middle to Upper Ordovician Loysburg 

Formation, the Upper Ordovician Hatter, Snyder, and 

Linden Hall Formations (all of the Black River Group, 

as used by Laughrey and others, 2003), and the overlying Upper Ordovician Nealmont, Salona, and Coburn 

Formations (all of the Trenton Group, as used by 

Laughrey and others, 2003). The Loysburg Formation 

grades into the lower portion of the Black River Group 

in New York State. We chose to follow the Black River 

and Trenton Group nomenclature of Laughrey and others (2003) because we were not able to identify formation contacts in the subsurface of central Pennsylvania.

The Loysburg Formation includes a lower Milroy 

(or “Tiger-Striped”) Member and an upper Clover 

Member (Wagner, 1966; Rones, 1969; Berg and others, 

1980). The Milroy Member is composed of alternating 

beds of dolomite and limestone with differential weathering creating a banded or striped appearance. The top 

of the unit is easily identified by a silty dolomitic limestone or dolomite with high peaks on gamma-ray logs 

(Wagner, 1966). Siltstone beds (20 to 30 ft thick) were 

observed at the top of the Milroy Member on lithologic 

logs created by the Geological Sample Log Company 

in drill holes 8 and 9. On these logs, the Milroy 

Member is also described as argillaceous dolomite and 

limestone. High gamma-ray peaks at the same locations 

on logs for drill holes 7, 8, and 9 were also observed. 

A siltstone layer was recognized on the lithologic log 

for drill hole 6 in Steuben County, New York, marking 

the top of the argillaceous lower portion of the Black 

River Group, which is interpreted to be equivalent to 

the Milroy Member of the Loysburg Formation in 

Pennsylvania.

The Clover Member of the Loysburg Formation 

is a microcrystalline to finely crystalline limestone 
10 Geologic Cross Section A–A′ Through the Appalachian Basin

(Wagner, 1966; Rones, 1969; Berg, 1980). When the 

underlying and overlying units are less dolomitic, it is 

difficult to differentiate the Milroy Member from these 

units (Wagner, 1966). In the Pennsylvania portion of 

cross section A–A′, we grouped the Clover Member of 

the Loysburg Formation with the overlying Black River 

Group. The Milroy Member of the Loysburg Formation is shown as a separate recognizable unit between 

the underlying Bellefonte Formation and the overlying 

Black River Group.

Across north-central Pennsylvania and central 

New York, the Black River and Trenton Groups are 

characterized by a relatively homogeneous lithology 

(Riley and others, 2006). In cross section A–A′, the 

Black River Group consists mainly of carbonate 

mudstone and wackestone, whereas the Trenton Group 

consists mainly of fossiliferous, argillaceous limestone (wackestone, packstone, and grainstone). In 

New York, the lower 100 to 150 ft of the Black River 

Group consists of argillaceous and dolomitic limestone 

that extends across cross section A–A′ from the Pennsylvania State line to drill hole 1 (fig. 3). This lower 

unit is considered in this publication to be equivalent 

to the Milroy Member of the Loysburg Formation in 

Pennsylvania. We considered the overlying nonargillaceous portion of the Black River Group to be 

partially equivalent to the Clover member of the Loysburg Formation in Pennsylvania. Two marker beds of 

unknown lithology, labelled marker X and marker Y on 

the cross section, are recognized in the upper two-thirds 

of the Black River Group from the Allegheny structural 

front to drill hole 1. On the cross section and in figure 

3, three widespread bentonite beds are shown in the 

Trenton Group, a lower unnamed bentonite bed (possibly the Ocoonita or Hockett beds of Kolata and others, 

1996), the middle Deicke and upper Millbrig Bentonite 

beds (Huff and Kolata, 1990; Kolata and others, 1996).

Limestones of the Black River and Trenton 

Groups are interpreted as subtidal-carbonate-ramp and 

deeper water carbonate-ramp to shelf-margin deposits, 

respectively (Laughrey and others, 2003; Riley and others, 2006). The bentonite beds are thought to be derived 

from extensive volcanic ash falls that occurred during 

the Late Ordovician part of the Taconic orogeny (Huff 

and Kolata, 1990; Huff and others, 1992). The southeastward-thickening wedge of carbonate-dominated 

strata from the base of the Lower and Middle Cambrian 

Warrior Formation and the equivalent Galway Formation through the Upper Ordovician Trenton Group is 

interpreted as deposits of a post-rift passive margin 

sequence (Read, 1989a, b). Middle Ordovician continental-scale erosion of this passive margin forming the 

Knox unconformity occurred during a drop in eustatic 

sea level and (or) tectonic uplift that preceded the 

Taconic orogeny (Harris and Repetski, 1982; Mussman 

and others, 1988; Read 1989a, b).

Upper Ordovician to Lower Silurian 

Siliciclastic Strata

The Upper Ordovician to lower Silurian siliciclastic strata are characterized by gray shale, red shale, 

sandstone, and black shale (fig. 3). As shown on cross 

section A–A′, the combined thickness of the strata 

ranges from about 4,250 ft in the vicinity of the Allegheny structural front to about 2,000 ft near drill hole 1. 

In drill hole 9, about 3,500 ft of Upper Ordovician to 

lower Silurian siliciclastic strata have been penetrated. 

In the Pennsylvania part of cross section A–A′, the 

Upper Ordovician to lower Silurian siliciclastic strata 

consist of the following units (in ascending order): 

the Utica (Antes) Shale, Reedsville Shale, Bald Eagle 

Formation, Juniata Formation, Tuscarora Formation, 

Rose Hill Formation, Keefer Formation, and Rochester 

Member of the Mifflintown Formation (Cotter, 1982; 

Berg and others, 1983; Ryder, 1992; Hettinger, 2001) 

(fig. 3). In New York, the Upper Ordovician to lower 

Silurian siliciclastic strata nomenclature is as follows: 

(1) Utica Shale is used instead of Utica (Antes) Shale, 

(2) Lorraine Shale is used instead of Reedsville Shale, 

(3) Oswego Sandstone is used instead of Bald Eagle 

Formation, (4) Queenston Shale is used instead of Juniata Formation, (5) Medina Group (including, in ascending order, the Whirlpool sandstone [where present; 

only identified in the drill hole 4 well logs], Grimsby 

Sandstone, Thorold Sandstone, and Cambria Shale; 

Ryder, 2004) is used instead of Tuscarora Formation, 

and (6) Clinton Group (including, in ascending order, 

the lower unnamed shale, Reynales Limestone, middle 

unnamed shale, Irondequoit Limestone, and Rochester 

Shale; Ryder, 2000) is used instead of Rose Hill Formation, Keefer Formation (equivalent to the Irondequoit 

Limestone), and Rochester Member of the Mifflintown 

Formation (Fisher, 1977) (fig. 3).

The Upper Ordovician to lower Silurian siliciclastic strata are interpreted as being derived from an 

eastern orogenic source and deposited in a rapidly 

subsiding foreland basin (Castle, 2001). This foreland 

basin and its sedimentary deposits are associated with 

the continent-island arc collision of the Taconic orogeny (Colton, 1970; Milici and de Witt, 1988; Drake and 

others, 1989; Faill, 1997a).

The Utica (Antes) Shale, a black shale unit that 

is transitional with the underlying Trenton Group, 

extends across cross section A–A′ and ranges in thickness from about 150 ft in drill hole 1 to about 400 ft in 

the southeastern flank of the Rome trough (drill hole 9). 

The Utica (Antes) Shale recognized in cross section 

A–A′ is approximately equivalent to (in ascending 

order) the Logana Member of the Lexington Formation, the Point Pleasant Formation, and the Utica Shale 

proper (Patchen and Carter, 2015). We chose not to 

use the Point Pleasant Formation nomenclature of 

Patchen and Carter (2015) because this name was only 

recently extended to western New York and northeastern Pennsylvania from its original usage in western 

Ohio (Wickstrom and Gray, 1988; Wickstrom, 1990; 

Wickstrom and others, 1992). The sums of thicknesses of the Utica Shale and Point Pleasant Formation 
Stratigraphic Framework 11

shown on isopach maps and data tables in Patchen and 

Carter (2015) appear to be approximately the same 

as our thicknesses for the Utica Shale in drill holes 

1 through 9. In ascending order, Upper Ordovician 

strata that overlie the Utica (Antes) Shale consist of the 

Reedsville and equivalent Lorraine Shales (gray shale, 

siltstone, and minor sandstone), the Bald Eagle Formation and equivalent Oswego Sandstone (sandstone, 

siltstone, and gray shale), and the Juniata Formation 

and equivalent Queenston Shale (silty red shale). The 

widespread Cherokee unconformity (Dennison and 

Head, 1975; Brett and others, 1990) is present at the 

top of the Juniata Formation and equivalent Queenston 

Shale (Ryder, 2000; Hettinger, 2001). According to 

Dennison and Head (1975), the Cherokee unconformity 

resulted from a fall in eustatic sea level that probably 

was independent of the Taconic orogeny, creating the 

resultant classic angular unconformity between Upper 

Ordovician and lower Silurian rocks in eastern Pennsylvania (Pavlides and others, 1968).

The Utica (Antes) Shale is interpreted as an 

anoxic deposit that accumulated in the distal part of the 

Taconic foreland basin during initial deepening of the 

carbonate platform (Castle, 2001), whereas the overlying Reedsville and equivalent Lorraine Shales, Bald 

Eagle Formation and equivalent Oswego Sandstone, 

and the Juniata Formation and equivalent Queenston 

Shale are interpreted as shallow-marine and intertidal 

deposits that accumulated on a prograding clastic 

wedge (Diecchio, 1985; Castle, 2001).

The Tuscarora Formation, which is about 400 ft 

thick (including a 90-ft-thick Castanea Member at the 

top) in north-central Pennsylvania (near drill hole 9), 

thins northwestward to about 100 ft in west-central 

New York (near drill hole 1) where the rocks are 

assigned to the Medina Group, undivided.

The Rose Hill Formation consists of gray shale, 

red shale, dolomite, and limestone (Hettinger, 2001; 

Ryder, 2004; Ryder and others, 2012). On this 

cross section, the Rose Hill Formation consists of 

(in ascending order) a lower limestone member, a 

lower shale member, an upper limestone member, and 

an upper shale member. The lower limestone member 

pinches out to the northwest between drill holes 6 

and 7, whereas in New York the overlying members 

correspond, respectively, to the lower unnamed shale, 

Reynales Limestone, and middle unnamed shale of 

the Clinton Group. Also, just west of drill hole 7, the 

Keefer Formation becomes more limy to the northwest and changes across an arbitrary boundary to 

the equivalent Irondequoit Limestone of the Clinton 

Group. The Rochester Member of the Mifflintown 

Formation in Pennsylvania also changes across an 

arbitrary boundary (just west of drill hole 7) to the 

Rochester Shale of the Clinton Group.

Lower Silurian to Middle Devonian 

Carbonate and Evaporite Strata

Lower Silurian to Middle Devonian strata consist 

of a lithologically varied interval of limestone, dolomite, sandstone, gray shale, chert, anhydrite, and halite 

(fig. 3). In the Pennsylvania part of cross section A–A′

(drill holes 8 and 9), the stratigraphic units in ascending 

order are as follows: lower and upper Silurian McKenzie Member of the Mifflintown Formation; upper 

Silurian Bloomsburg Formation; upper Silurian Wills 

Creek Formation (equivalent to the Vernon Shale of 

the Salina Group); upper Silurian Salina Group (Vernon Shale, Syracuse Salt, Camillus Shale, and Bertie 

Dolomite); upper Silurian to Lower Devonian Keyser 

Formation; Lower Devonian New Creek Limestone, 

Corriganville Limestone, Mandata Shale, Shriver 

Chert, and Oriskany Sandstone; and Middle Devonian 

Onondaga Limestone (Berg and others, 1983) (fig. 3). 

In the Valley and Ridge province near drill hole 10 

(southeast of the Jersey Shore fault), the New Creek 

Limestone, Corriganville Limestone, Mandata Shale, 

Shriver Chert, and Oriskany Sandstone are changed 

to member status of Old Port Formation (with the 

Oriskany Sandstone renamed the Ridgely Member of 

the Old Port Formation) (Faill and others, 1977; Berg 

and others, 1983). Also, in this area, the Salina Group is 

replaced by the Tonoloway Limestone (Faill and others, 

1977; Berg and others, 1983). About 7 miles southeast 

of drill hole 7, we show an arbitrary boundary between 

the Vernon Shale of the Salina Group to the northwest 

and the Wills Creek Formation to the southeast. Also, 

about 6 miles southeast of drill hole 7, the Middle 

Devonian uppermost part of the Keyser Formation is 

absent perhaps because of non-deposition. We show the 

McKenzie Member of the Mifflintown Formation transitioning into the Lockport Dolomite (equivalent to the 

Lockport Group of New York) about 8 miles northwest 

of drill hole 7. At nearly the same location, we show 

the Bloomsburg Formation grading laterally into the 

Lockport Dolomite. In New York, the lower Silurian 

to Middle Devonian strata change nomenclature as 

follows: (1) the Lockport Dolomite in Pennsylvania is 

equivalent to the Lockport Group in New York; (2) the 

Wills Creek Formation in Pennsylvania is equivalent to 

the Vernon Shale of the Salina Group in New York; and 

(3) the Keyser Formation, New Creek Limestone, Corriganville Limestone, Mandata Shale, and Shriver Chert 

in Pennsylvania are equivalent to the Helderberg Group 

(undivided on cross section A–A′) in New York.

The Lockport Dolomite and Lockport Group 

consists mainly of fine to medium crystalline dolomite, 

several widespread vuggy rubble zones, and local bioherms (Laughrey, 1987). By comparison, the equivalent 

McKenzie Member of the Mifflintown Formation consists of carbonate mudstone and fossiliferous wackestone to grainstone interbedded with greenish-gray to 

black shale (Knowles, 1966; de Witt, 1974). We show 

the facies change from limestone and shale of the McKenzie Member of the Mifflintown Formation to dolomite of the Lockport Dolomite and Lockport Group 

approximately 8 miles northwest of drill hole 7.
12 Geologic Cross Section A–A′ Through the Appalachian Basin

The upper Silurian Bloomsburg Formation is 

characterized by grayish-red shale, mudstone, and 

sandstone (Hoskins, 1961; Knowles, 1966; de Witt, 

1974). On cross section A–A′ the Bloomsburg Formation is interpreted to be about 450 ft thick northwest 

of the Allegheny structural front and thins to the 

northwest to about 100 ft between drill holes 6 and 7, 

before it grades laterally into the upper portion of the 

Lockport Dolomite.

The upper Silurian Salina Group and the Wills 

Creek Formation (equivalent to the Vernon Shale of 

the Salina Group) constitute a well-defined unit that 

extends across all of cross section A–A′ and ranges 

in thickness from about 2,000 to 2,700 ft near the 

Allegheny structural front where it is over-thickened by 

flowage and thin-skinned deformation, to about 400 ft 

in west-central New York (drill hole 1). The portion 

of the Salina Group above the Vernon Shale overlies 

an extensive detachment zone that is responsible for 

multiple Alleghanian folds and imbricate splay faults 

in upper Silurian and Devonian strata previously 

described in the thin-skinned structures section. The 

Salina Group consists mainly of anhydritic dolomite 

and shale, anhydrite, and halite. The Vernon Shale of 

the Salina Group consists of anhydritic and dolomitic 

gray shale or mudstone. Its southeastern equivalent, the 

upper Silurian Wills Creek Formation, consists of anhydritic and argillaceous dolomite. The halite-bearing 

part of the Syracuse Salt is concentrated in drill holes 3 

through 9. Cross section A–A′ passes through the Salina 

salt basin (as defined by Colton, 1970; Frey, 1973; Ege, 

1985; Cotter and Inners, 1986; Ryder and others, 2007; 

and Mount (2014)) from the northwest margin (drill 

holes 2 through 4) through the thickest portion of the 

basin (drill holes 5 through 9) in south-central New 

York and north-central Pennsylvania. Halite-bearing 

intervals in drill holes 3 through 9 are interpreted from 

geophysical and lithologic logs and from halite beds 

previously identified by Heyman (1977). Most halitebearing intervals shown on section A–A′, such as the 

approximately 1,100-ft-thick interval in drill hole 7, are 

not composed entirely of halite but instead are intervals 

of interbedded halite, dolomite, shale, and anhydrite. 

Non-halite-bearing portions of the Syracuse Salt are 

composed of dolomite and shale, which totally dominate the formation in drill holes 1 through 3. Overlying 

the Syracuse Salt is the Camillus Shale composed of 

anhydritic and dolomitic shale. We interpreted a zone 

of higher gamma-ray peaks in drill holes 3 through 9 

as defining the range of the Camillus Shale. The Bertie 

Dolomite (anhydritic dolomite and limestone, where 

present) immediately overlies the Camillus Shale and 

underlies the Keyser Formation in Pennsylvania, and 

the Helderberg Group and the Akron Dolomite in 

New York. We recognized fairly thick sections (100 to 

150 ft) of the Bertie Dolomite in Pennsylvania (drill 

holes 7 through 9), but it was mostly absent in New 

York except for fairly thin sections (8 to 43 ft) in two 

drill holes (3 and 4).

Most of the Keyser Formation that overlies the 

Salina Group is late Silurian in age, based on conodont 

studies (Denkler and Harris, 1988). In north-central 

Pennsylvania, the Keyser Formation is limestone that 

consists of carbonate mudstone and fossiliferous grainstone (Knowles, 1966; de Witt, 1974; Laughrey, 1999). 

The Keyser Formation of Pennsylvania is equivalent 

to the lower portion of the Helderberg Group in New 

York. The Helderberg Group is also equivalent to the 

upper Silurian Akron Dolomite in New York, an argillaceous dolomite (80-ft-thick or less) that extends from 

midway between drill holes 4 and 5 to the western end 

of the cross section between drill holes 2 and 3.

The overall depositional setting of the lower 

Silurian to Middle Devonian carbonate and evaporite 

rocks was a shallow basin with closed circulation 

where evaporites were surrounded by a carbonate shelf 

with normal seawater where limestone was deposited 

(Smosna and others, 1977). Dolomites and evaporite 

beds of the upper Silurian Salina Group that overlie 

the Lockport Dolomite and Lockport Group signal an 

abrupt change on the carbonate shelf from normal 

circulation to greatly restricted circulation caused by a 

change to a very arid climate (Cecil and others, 2004).

Lower Devonian limestones in cross section A–A′

constitute a composite unit about 200 ft thick between 

drill hole 3 and the Allegheny structural front. The 

New Creek and Corriganville Limestones near the base 

of the composite unit consist of wackestone, packstone, and skeletal grainstone; the Shriver Chert at the 

top of the composite unit consists of silty limestone 

and siliceous shale with abundant chert (Knowles, 

1966; de Witt, 1974; Harper, 1999). The Corriganville 

Limestone is overlain by the thin, dark-gray to black 

Mandata Shale (Harper, 1999). The Helderberg Group 

in Steuben County, New York, is generally interpreted 

as a normal marine deposit that accumulated in an 

intracratonic basin and on flanking carbonate shelves 

(Smosna, 1988).

The clean, quartzose Lower Devonian Oriskany 

Sandstone, also known as the Ridgeley Sandstone in 

Pennsylvania (Berg and others, 1983; Harper and 

Patchen, 1996; Harper, 1999), unconformably overlies 

the Helderberg Group and extends across most of cross 

section A–A′. Regional unconformities at the top and 

base of the Oriskany Sandstone probably were caused 

by falls in eustatic sea level (Dennison and Head, 

1975). Of the two unconformities, Dennison and Head 

(1975) considered the upper one to represent the longer 

period of emergence and perhaps the greater decrease 

in water depth. This post-Oriskany unconformity 

probably truncated the Oriskany Sandstone between 

drill holes 3 and 4 near the pinchout of the Oriskany 

Sandstone mapped by Opritza (1996) and Harper and 

Patchen (1996). They show the Oriskany Sandstone to 

be absent at the locations of drill holes 1 through 5 

except for a small area between drill holes 3 and 4. 

However, a lithologic log of rocks encountered in drill 

hole 5 from the Geological Sample Log Company 

clearly identified a white, medium- to coarse-grained 

sandstone as the Oriskany Sandstone. Therefore, we 
Stratigraphic Framework 13

chose to show the Oriskany Sandstone as present in 

drill hole 4 and drill holes 6 through 9. Northwest of 

drill hole 4 where the Oriskany Sandstone pinches out, 

the two unconformities merge and cut progressively 

downsection across the uppermost part of the Akron 

Dolomite. The Oriskany Sandstone has been interpreted 

as a shallow-marine deposit (Harper and Patchen, 

1996), although Cecil (2004a, b) suggested an earlier 

eolian provenance for the Oriskany Sandstone and 

underlying chert beds of the Shriver Chert.

The Oriskany Sandstone is overlain unconformably by a thin, argillaceous, slightly fossiliferous 

limestone, which is recognized as the Middle Devonian Onondaga Limestone (Flaherty, 1996; Harper 

and Patchen, 1996). Near drill hole 1, the Onondaga 

Limestone forms the uppermost bedrock unit below a 

thin veneer of Quaternary sediments (Fisher and others, 1970). Near drill hole 2, this unit was removed by 

erosion in the Black Creek valley (fig. 1). Southeast of 

drill hole 2, the Onondaga Limestone extends across 

cross section A–A′ all the way to the Allegheny structural front and is also present in the Jersey Shore fault 

block southeast of the front. Warters (1972) and Van 

Tyne (1996) have documented the presence of a trend 

of pinnacle reefs in the Onondaga in Steuben County, 

New York.

Middle Devonian to Lower Mississippian 

Siliciclastic Strata

Middle Devonian to Lower Mississippian siliciclastic strata include black shale, gray shale, sandstone, 

siltstone, red beds, and minor argillaceous limestones 

(fig. 3). These Middle Devonian to Lower Mississippian strata shown in cross section A–A′ thin dramatically northwestward from as much as about 7,900 ft 

in drill hole 9 in north-central Pennsylvania to an 

incomplete section about 600 ft thick in drill hole 3 in 

west-central New York. In Pennsylvania, the Middle 

Devonian to Lower Mississippian siliciclastic strata 

include the following units (and their equivalents, in 

ascending order): (1) the Middle Devonian Hamilton 

Group (Marcellus Formation and Mahantango Formation), (2) the Middle Devonian Tully Limestone, (3) the 

Upper Devonian Genesee Formation (including the 

Geneseo Shale Member, Lodi Limestone Member, 

Penn Yan Shale Member, Genundewa Limestone 

Member, and West River Shale Member), (4) Upper 

Devonian Sonyea Formation (Middlesex Shale Member only), (5) Upper Devonian Brallier Formation, 

(6) Upper Devonian Lock Haven Formation, (7) Upper 

Devonian Catskill Formation, (8) Upper Devonian and 

Lower Mississippian Huntley Mountain Formation, and 

(9) the Lower Mississippian Burgoon Sandstone. New 

York equivalents of the Middle Devonian to Lower 

Mississippian strata in Pennsylvania include the following units (in ascending order): (1) the Middle Devonian Hamilton Group, including the Marcellus Shale, 

Skaneateles Shale (including the Stafford Limestone 

Member), Ludlowville Shale (including the Centerfield 

Limestone Member), and Moscow Shale (including the 

Tichenor Limestone Member); (2) Middle Devonian 

Tully Limestone; (3) Upper Devonian Genesee Formation (Geneseo Shale Member, Lodi Limestone Member, Penn Yan Shale Member, Genundewa Limestone 

Member, and West River Shale Member); (4) Upper 

Devonian Sonyea Formation (Middlesex Shale Member 

and Cashaqua Shale Member); (5) the Upper Devonian West Falls Formation (including the Rhinestreet 

Shale Member, Hatch Shale Member, Grimes Siltstone 

Member, Gardeau Shale Member, West Hill Member, 

and Nunda Sandstone Member); (6) Upper Devonian 

Java Formation (Pipe Creek Shale and Wiscoy Sandstone Members); and (7) Upper Devonian Perrysburg 

Formation (Dunkirk Shale and unnamed overlying 

shale members). No Mississippian strata are present in 

the New York part of cross section A–A′ due to erosion. 

The top of the Tully Limestone marks the top of the 

Middle Devonian on cross section A–A′ (fig. 3). Also, 

the Brallier Formation of Pennsylvania is interpreted 

to be equivalent to the Cashaqua Shale Member of the 

Sonyea Formation through the Gardeau Shale Member 

of the West Falls Formation in New York. Furthermore, 

the Lock Haven Formation of Pennsylvania is interpreted to be equivalent to the West Hill Member of the 

West Falls Formation through the Perrysburg Formation in New York.

The Upper Devonian to Lower Mississippian 

siliciclastic strata are interpreted as sediments derived 

from an eastern orogenic source and deposited in a 

rapidly subsiding foreland basin. This foreland basin 

and its sedimentary deposits (the Catskill delta complex 

of Woodrow and Sevon (1985) and Harper (1999)) are 

associated with the Acadian orogeny (Colton, 1970; 

Milici and de Witt, 1988; Osberg and others, 1989; 

Faill, 1997b).

The stratigraphy of the Middle and Upper 

Devonian black shales has been studied in great detail 

because of the role of black shales as hydrocarbon 

source rocks and reservoirs (Roen and Kepferle, 1993). 

In the vicinity of the Allegheny structural front and 

the adjoining Valley and Ridge province, the lowermost of the Devonian black shales is the Middle 

Devonian Marcellus Formation, which rests conformably on the Middle Devonian Onondaga Limestone. 

Also, in this region, the widespread Tioga Bentonite 

Bed (Tioga Bentonite of Dennison and Head, 1975) is 

often present in either the Marcellus Formation or the 

Onondaga Limestone (Inners, 1979; Way and others, 

1986; Harper and Patchen, 1996). This bentonite 

bed is shown on cross section A–A′ and in figure 3 in 

Pennsylvania only. A metabentonite bed (presumably 

the Tioga bentonite) was identified on lithologic logs 

from the Geologic Sample Log Company in drill holes 

8 and 9, but was not present in lithologic logs for drill 

holes 3, 4, and 6 (we did not have lithologic logs for 

drill holes 5 and 7, and the Marcellus Shale [Formation] and Onondaga Limestone are not present in drill 

holes 1, 2, and 10). Within the Marcellus Shale two 
14 Geologic Cross Section A–A′ Through the Appalachian Basin

limestone members are identifiable on well logs for 

drill holes 7 through 9, which include the lower Cherry 

Valley Limestone Member and the upper Purcell 

Limestone Member (as recognized by deWitt and Roen 

(1993)). We list elevations for these two limestone 

members and the unnamed shale members (that they 

separate) in appendix A, but we chose not to show 

them on cross section A–A′ or the correlation chart 

(fig. 3), because they are extremely thin subunits of an 

already thin formation.

On cross section A–A′, we show the Marcellus 

Formation and the overlying gray shale of the Mahantango Formation of the Hamilton Group near 

the Allegheny structural front, but in drill holes 7 

through 9, we chose to extend the use of the formation 

names within the Hamilton Group of New York southward into Pennsylvania because the New York formations are easily identifiable on the gamma-ray logs of 

those three drill holes. The following formations are 

included in the Hamilton Group in New York, and we 

recognize them near drill holes 7 through 9 (in ascending order): (1) the Marcellus Shale, (2) the Skaneateles 

Shale, (3), the Ludlowville Shale, and (4) the Moscow 

Shale. Basal limestone members of the top three formations (as recognized by deWitt and Roen (1993)) were 

identifiable on well logs and used to determine formation contacts in drill holes 3 through 5 and 7 through 9 

(no well logs were available above the Marcellus Shale 

in drill hole 6). The basal limestone members include 

the following (in ascending order): (1) the Stafford 

Limestone Member of the Skaneateles Shale, (2) the 

Centerfield Limestone Member of the Ludlowville 

Shale, (3) and the Tichenor Limestone Member of the 

Moscow Shale. In drill holes 5, 6, 7, and 9, we were 

also able to identify the Menteth Limestone Member 

of the Moscow Shale which separates the upper shale 

member from the lower Deep Run Shale Member (as 

recognized by deWitt and Roen (1993)). We listed the 

elevations of these members in appendix A, but because 

they are so thin we chose not to represent them on cross 

section A–A′ or the correlation chart (fig. 3).

We also chose to extend the use of the following 

New York names into Pennsylvania in drill holes 7 

through 9: (1) Geneseo Shale Member, Lodi Limestone Member, Penn Yan Shale Member, Genundewa 

Limestone Member, and West River Shale Member 

of the Genesee Formation; and (2) Middlesex Shale 

Member of the Sonyea Formation. We chose not to use 

the name Burket Shale Member of the Harrell Formation (equivalent to Geneseo Shale Member). The 

black shales of the Marcellus Shale, Geneseo Shale 

Member of the Genesee Formation, and Middlesex 

Shale Member of the Sonyea Formation are interpreted 

as anoxic basin deposits in Pennsylvania (Boswell, 

1996; Harper, 1999), whereas the overlying Brallier 

Formation is interpreted as a marine-basin-slope to 

turbidite-slope to delta-front deposit (Lundegard and 

others, 1985; Harper, 1999). In New York, several other 

black shales (the Rhinestreet Shale Member of the West 

Falls Formation, Pipe Creek Shale Member of the Java 

Formation, and Dunkirk Shale Member of the Perrysburg Formation [equivalent to the Huron Member of 

the Ohio Shale]) are present above the already mentioned Marcellus Shale, Geneseo Shale Member, and 

the Middlesex Shale Member. Several of these black 

shales have been of interest for their potential shale-gas 

deposits (Roen, 1984; de Witt and Roen, 1985; de Witt 

and others, 1993; Wrightstone, 2015).

A regional Middle to Late Devonian unconformity, 

described and mapped by de Witt and others (1993), is 

present throughout all of cross section A–A′ at the top 

of the Tully Limestone (base of the Genesee Formation) 

and at the top of the Hamilton Group where the Tully 

Limestone is absent (fig. 3). We did not use the unconformity symbol on cross section A–A′ northwest of well 

5 because it would be thicker than the Tully Limestone unit. Cooper and Williams (1935) and de Witt 

and others (1993) show the Tully Limestone absent 

north and west of Canandaigua Lake in New York, 

but the gamma-ray logs for drill hole 3 in Livingston 

County indicate the presence of a thick limestone at the 

appropriate stratigraphic position. Thus, we chose to 

show the Tully Limestone at drill hole 3. However, we 

suggest that the Tully Limestone is only present locally 

in erosional remnants in this area, and one of these remnants may have been penetrated by drill hole 3.

Erosion has removed the West Falls, Java, and 

Perrysburg Formations northwest of drill hole 4, and 

removed strata of the Hamilton Group, Tully Limestone, Genesee Formation, and Sonyea Formation 

between drill holes 2 and 3.

The Lock Haven Formation in Pennsylvania and 

the equivalent West Hill Member and Nunda Sandstone Member of the West Falls Formation, Wiscoy 

Sandstone Member of the Java Formation, and Perrysburg Formation in New York consist of interbedded 

sandstone, siltstone and gray shale. Sandstone beds of 

the Scherr and Foreknobs Formations in central and 

southern Pennsylvania (equivalent to the Lock Haven 

Formation) are interpreted as shallow-water marine 

to shoreline, fluvial-deltaic, delta-front, and tidal-flat 

deposits (Harper, 1999). Black shale deposits of the 

Pipe Creek Member of the Java Formation and the 

Dunkirk Shale Member of the Perrysburg Formation in 

New York, also equivalents of the Lock Haven Formation in Pennsylvania, are interpreted as anoxic basin 

deposits (Boswell, 1996; Harper, 1999). The Catskill 

Formation that overlies the Lock Haven Formation 

consists of interbedded redbeds of sandstone, siltstone, 

and shale, and local gray to green shale. The Catskill 

Formation redbeds are interpreted as exposed alluvialplain, fluvial, and fluvial-deltaic deposits (Slingerland 

and Loulé, 1988; Harper, 1999).

The Upper Devonian to Lower Mississippian 

Huntley Mountain Formation is present in several 

Allegheny Plateau highland areas on cross section A–A′

between drill holes 6 and 10 and is completely eroded 

in New York. The Huntley Mountain Formation consists mainly of argillaceous sandstone and is interpreted 

as fluvial and estuarine deposits (Berg, 1999).

The Lower Mississippian Burgoon Sandstone is 

present on several Allegheny Plateau highland areas on 

cross section A–A′ between drill holes 8 and 10, where 
References Cited 15

the sandstone is locally truncated by the Middle Mississippian unconformity and the overlying Middle and 

Upper Mississippian Mauch Chunk Formation (fig. 3). 

The location of the truncated margin of the Burgoon 

Sandstone is consistent with the northeast-trending 

truncated margin of the Burgoon shown by Brezinski 

(1999). The Burgoon Sandstone is interpreted as a 

braided-fluvial deposit (Berg, 1999; Brezinski, 1999).

Middle and Upper Mississippian and 

Pennsylvanian Siliciclastic Strata

The Middle and Upper Mississippian and Pennsylvanian siliciclastic strata on cross section A–A′

consist of sandstone, red and gray shale, and coal 

(fig. 3). These strata are only a few hundred feet thick 

because they are deeply eroded. These Mississippian 

and Pennsylvanian strata include the following units 

(in ascending order): the Middle and Upper Mississippian Mauch Chunk Formation; the Lower and Middle 

Pennsylvanian Pottsville Formation, and the Middle 

Pennsylvanian Allegheny Formation (fig. 3).

The Middle and Upper Mississippian and Pennsylvanian siliciclastic strata are predominantly nonmarine sediments derived from an easterly source and 

deposited in a rapidly subsiding foreland basin. This 

foreland basin and its sedimentary deposits are associated with the Alleghanian orogeny (Colton, 1970; 

Milici and de Witt, 1988; Hatcher and others, 1989; 

Faill, 1997b, 1998).

The Middle and Upper Mississippian Mauch 

Chunk Formation rests conformably on the Lower 

Mississippian Burgoon Sandstone at a few Allegheny 

Plateau uplands 8 to 10 mi southeast of drill hole 9. 

The Mauch Chunk Formation consists of red and gray 

shale and local sandstone deposited in an alluvial 

environment.

The Lower and Middle Pennsylvanian Pottsville 

Formation (which consists of red sandstone; red conglomeratic sandstone; sandy gray shale; gray shale; and 

minor coal) unconformably overlies the Mauch Chunk 

Formation in Pennsylvania. The widespread unconformity at the base of the Pottsville Formation is known 

by various names that include the basal Pennsylvanian 

unconformity (Brezinski, 1999), the sub-Pennsylvanian 

unconformity (Beuthin, 1994), the Mississippian-Pennsylvanian unconformity (Rice and Schwietering, 1988), 

and the Lower Pennsylvanian unconformity (this report 

and Edmunds and others, 1999). The Pottsville Formation is only several hundred feet thick on cross section 

A–A′ in Pennsylvania where it crops out on three mountaintops in the Jersey Mills syncline southeast of drill 

hole 9, and on a mountaintop in the Pine Creek syncline 

between drill holes 6 and 7.

The Middle Pennsylvanian Allegheny Formation 

(which consists of gray shale, sandstone, coal, and local 

thin limestone) comformably overlies the Pottsville 

Formation. Along cross section A–A′, the Allegheny 

Formation is only present on a mountaintop in the Pine 

Creek syncline northwest of drill hole 7. Strata of the 

Allegheny Formation are interpreted as alluvial-plain, 

delta-plain, marginal-marine, and peat-swamp deposits 

(Edmunds and others, 1999).

Acknowledgments

We wish to thank Robert Jacobi of the State 

University of New York at Buffalo for his insightful 

comments and contributions to the New York portion 

of cross section A–A′, and for his advice with respect 

to the faults and structural features of New York and 

northern Pennsylvania. We also wish to thank Jim 

Hnat, Chris Gonsalves, and Katy Keller of Shell Oil 

Corporation for their insightful comments and contributions to the Pennsylvania portion of cross section 

A–A′. We would also like to thank Bob Grundy of 

Inflection Energy LLC and Jim Hnat for sharing with 

us the LAS file for the lower portion of the Harry P. 

Dewey well.

References Cited

Beardsley, R.W., and Cable, M.S., 1983, Overview of 

the evolution of the Appalachian basin: Northeastern 

Geology, v. 5, nos. 3‒4, p. 137–145.

Berg, T.M., 1999, Devonian-Mississippian transition, 

chap. 8 of Shultz, C.H., ed., The geology of Pennsylvania: Pennsylvania Geological Survey and 

Pittsburgh Geological Society Special Publication 1, 

p. 128–137.

Berg, T.M., Edmunds, W.E., Geyer, A.R., Glover, A.D., 

Hoskins, D.M., MacLachlan, D.B., Root, S.I., Sevon, 

W.D., and Socolow, A.A., comps., 1980, Geologic 

map of Pennsylvania: Pennsylvania Department 

of Environmental Resources Topographic and 

Geologic Survey Map 1, 3 sheets, scale 1:250,000. 

[Also available at http://www.dcnr.pa.gov/Geology/

PublicationsAndData/Pages/default.aspx.]

Berg, T.M., McInerney, M.K., Way, J.H., and MacLachlan, D.B., 1983, Stratigraphic correlation chart of 

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Appendix 1. Table Summarizing Stratigraphic Units and Depths of 

Stratigraphic Units for Drill Holes 1–10 in Cross Section A–A′

Blank cells indicate no formation was encountered in the drill hole.
28 Geologic Cross Section A–A′ Through the Appalachian Basin

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number 1 2 3 4 5 

American Petroleum Institute 

well number 31–037–05117 31–037–04593 31–051–04552 31–051–04630 31–101–21496 

Lease name No. 1 J. Klotzbach No. 1 L. Tyler No. 1 Albert McClurg No. 1 Arthur N. Kennedy No. 1 Hubbard 

Permanent datum GL GL GL GL GL 

Ground level elevation (ft) 862 703 988.5 599 1,760 

Kelly bushing elevation (ft) 870 716 1,003 612 1,775 

Measured from KB KB KB KB KB 

Drill depth (ft) 3,950 4,000 5,648 6,387 10,061 

Formation 1 Onondaga Limestone and Bois 

Blanc Formation 

Salina Group (Syracuse Salt) 

(anhydritic dolomite and shale)

Cashaqua Shale Member of the 

Sonyea Formation

Cashaqua Shale Member of the 

Sonyea Formation

Wiscoy Sandstone Member of 

the Java Formation

System or series: Middle Devonian upper Silurian Upper Devonian Upper Devonian Upper Devonian 

Formation top (relative to KB) (ft) -8 -13 -14 -13 -15 

Formation top (relative to GL) (ft) 0 0 0 0 0 

Formation top (relative to SL) (ft) 862 703 989 599 1,760 

Formation 2 Akron Dolomite (unconformity) Salina Group (Vernon Shale) 

(green shale and anhydritic 

dolomite)

Middlesex Shale Member of the 

Sonyea Formation

Middlesex Shale Member of the 

Sonyea Formation

Pipe Creek Shale Member of 

the Java Formation

System or series: upper Silurian upper Silurian Upper Devonian Upper Devonian Upper Devonian 

Formation top (relative to KB) (ft) -46 -173 -60 -136 -153 

Formation top (relative to GL) (ft) -38 -160 -46 -123 -138 

Formation top (relative to SL) (ft) 824 543 943 476 1,622 

Formation 3 Salina Group (Camillus Shale) Lockport Group (dolomite) West River Shale Member of the 

Genesee Formation1

West River Shale Member of the 

Genesee Formation1

Nunda Sandstone Member of the 

West Falls Formation

System or series: upper Silurian lower and upper Silurian Upper Devonian Upper Devonian Upper Devonian 

Formation top (relative to KB) (ft) -70 -293 -76 -172 -226 

Formation top (relative to GL) (ft) -62 -280 -62 -159 -211 

Formation top (relative to SL) (ft) 800 423 927 440 1,549 
Appendix 1. 29

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number 6 7 8 9 10

American Petroleum Institute 

well number 31–101–03924 37–117–20057 37–105–20182 37–035–20276 37–081–90002

Lease name No. 1 Robert Olin No. 1 Harry P. Dewey No. 1 Pa. Dept. of Forest and 

Water Tract 129

No. 1 Pa. State Forest, 

Tract 285–1 No. 1 W.E. Snyder

Permanent datum GL GL GL GL DF

Ground level elevation (ft) 1,645 1,569 1,847 2,004 726

Kelly bushing elevation (ft) 1,658 1,587 1,870 2,037 726

Measured from KB KB KB KB KB

Drill depth (ft) 13,508 15,082 18,834 19,360 5,808

Formation 1 Wiscoy Sandstone Member of 

the Java Formation

Catskill Formation (red 

sandstone, siltstone, and shale) 

and Lock Haven Formation 

(sandstone)

Huntley Mountain Formation Mauch Chunk Formation (red 

and gray shale)

Beekmantown Group (Bellefonte 

Formation) (upper part)

System or series: Upper Devonian Upper Devonian Lower Mississippian Mississippian Middle Ordovician

Formation top (relative to KB) (ft) -13 -18 -24 -33 0

Formation top (relative to GL) (ft) 0 0 -1 0 0

Formation top (relative to SL) (ft) 1,645 1,569 1,846 2,004 726

Formation 2 Pipe Creek Shale Member of the 

Java Formation

Lock Haven Formation (shale 

and siltstone)

Catskill Formation (red 

sandstone, siltstone, and shale)

Burgoon Sandstone Beekmantown Group (Bellefonte 

Formation) (lower part)

System or series: Upper Devonian Upper Devonian Upper Devonian Lower Mississippian Middle Ordovician

Formation top (relative to KB) (ft) -815 -694 -140 -150 -300

Formation top (relative to GL) (ft) -802 -676 -117 -117 -300

Formation top (relative to SL) (ft) 843 893 1,730 1,887 426

Formation 3 West Falls, Sonyea, and Genesee 

Formations (undivided)

Lock Haven Formation 

(sandstone, siltstone, and shale)

Lock Haven Formation 

(sandstone, siltstone, and shale)

Huntley Mountain Formation 

(argillaceous sandstone )

Beekmantown Group (Axemann 

Formation) (limestone)

System or series: Upper Devonian Upper Devonian Upper Devonian Lower Mississippian Middle Ordovician

Formation top (relative to KB) (ft) -865 -1,100 -1,142 -442 -1,320

Formation top (relative to GL) (ft) -852 -1,082 -1,119 -409 -1,320

Formation top (relative to SL) (ft) 793 487 728 1,595 -594
30 Geologic Cross Section A–A′ Through the Appalachian Basin

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number 1 2 3 4 5 

American Petroleum Institute 

well number 31–037–05117 31–037–04593 31–051–04552 31–051–04630 31–101–21496 

Lease name No. 1 J. Klotzbach No. 1 L. Tyler No. 1 Albert McClurg No. 1 Arthur N. Kennedy No. 1 Hubbard 

Permanent datum GL GL GL GL GL 

Ground level elevation (ft) 862 703 988.5 599 1,760 

Kelly bushing elevation (ft) 870 716 1,003 612 1,775 

Measured from KB KB KB KB KB 

Drill depth (ft) 3,950 4,000 5,648 6,387 10,061 

Formation 4 Salina Group (Syracuse Salt) 

(anhydritic dolomite and shale)

Clinton Group (Rochester Shale) Genundewa Limestone Member 

of the Genesee Formation1

Genundewa Limestone Member 

of the Genesee Formation1

West Hill Member of the West 

Falls Formation (shale and 

siltstone)

System or series: upper Silurian Silurian Upper Devonian Upper Devonian Upper Devonian 

Formation top (relative to KB) (ft) -140 -484 -106 -265 -439 

Formation top (relative to GL) (ft) -132 -471 -92 -252 -424 

Formation top (relative to SL) (ft) 730 232 897 347 1,336 

Formation 5 Salina Group (Vernon Shale) 

(green shale and anhydritic 

dolomite)

Clinton Group (Irondequoit 

Limestone)

Penn Yan Shale Member of the 

Genesee Formation1

Penn Yan Shale Member of the 

Genesee Formation1

West Falls Formation (undivided 

members below West Hill 

Member; shale and siltstone)

System or series: upper Silurian Silurian Upper Devonian Upper Devonian Upper Devonian 

Formation top (relative to KB) (ft) -278 -595 -108 -270 -658 

Formation top (relative to GL) (ft) -270 -582 -94 -257 -643 

Formation top (relative to SL) (ft) 592 121 895 342 1,117 

Formation 6 Lockport Group (dolomite) Clinton Group (middle unnamed 

shale)

Lodi Limestone Member of the 

Genesee Formation1

Lodi Limestone Member of the 

Genesee Formation1

Rhinestreet Shale Member of the 

West Falls Formation

System or series: lower and upper Silurian Silurian Upper Devonian Upper Devonian Upper Devonian 

Formation top (relative to KB) (ft) -510 -610 -126 -332 -1,830 

Formation top (relative to GL) (ft) -502 -597 -112 -319 -1,815 

Formation top (relative to SL) (ft) 360 106 877 280 -55 
Appendix 1. 31

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number 6 7 8 9 10

American Petroleum Institute 

well number 31–101–03924 37–117–20057 37–105–20182 37–035–20276 37–081–90002

Lease name No. 1 Robert Olin No. 1 Harry P. Dewey No. 1 Pa. Dept. of Forest and 

Water Tract 129

No. 1 Pa. State Forest, 

Tract 285–1 No. 1 W.E. Snyder

Permanent datum GL GL GL GL DF

Ground level elevation (ft) 1,645 1,569 1,847 2,004 726

Kelly bushing elevation (ft) 1,658 1,587 1,870 2,037 726

Measured from KB KB KB KB KB

Drill depth (ft) 13,508 15,082 18,834 19,360 5,808

Formation 4 Tully Limestone (unconformity) Barllier Formation (shale and 

siltstone)

Lock Haven Formation 

(siltstone)

Catskill Formation (red 

sandstone, siltstone, and shale)

Beekmantown Group (Nittany 

Formation)

System or series: Middle Devonian Upper Devonian Upper Devonian Upper Devonian Lower Ordovician

Formation top (relative to KB) (ft) -3,275 -2,510 2,600 -813 -2,234

Formation top (relative to GL) (ft) -3,262 -2,492 2,624 -780 -2,234

Formation top (relative to SL) (ft) -1,617 -923 4,470 1,224 -1,508

Formation 5 Hamilton Group (undivided 

formations above Marcellus 

Shale)

Middlesex Shale Member of the 

Sonyea Formation

Brallier Formation (shale and 

siltstone)

Lock Haven Formation 

(sandstone, siltstone, and shale)

Beekmantown Group 

(Stonehenge Formation) 

(limestone) (Knox unconformity)

System or series: Middle Devonian Upper Devonian Upper Devonian Upper Devonian Middle Ordovician

Formation top (relative to KB) (ft) -3,330 -3,702 -3,970 -2,138 -2,640

Formation top (relative to GL) (ft) -3,317 -3,684 -3,947 -2,105 -2,640

Formation top (relative to SL) (ft) -1,672 -2,115 -2,100 -101 -1,914

Formation 6 Hamilton Group (Marcellus 

Shale)

West River Shale and 

Genundewa Limestone Members 

(undivided) of the Genesee 

Formation1

Middlesex Shale Member of the 

Sonyea Formation

Lock Haven Formation 

(siltstone)

Beekmantown Group (Larke 

Formation)

System or series: Middle Devonian Upper Devonian Upper Devonian Upper Devonian Lower Ordovician

Formation top (relative to KB) (ft) -3,970 -4,002 -4,589 -3,354 -2,670

Formation top (relative to GL) (ft) -3,957 -3,984 -4,566 -3,321 -2,670

Formation top (relative to SL) (ft) -2,312 -2,415 -2,719 -1,317 -1,944
32 Geologic Cross Section A–A′ Through the Appalachian Basin

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number 1 2 3 4 5 

American Petroleum Institute 

well number 31–037–05117 31–037–04593 31–051–04552 31–051–04630 31–101–21496 

Lease name No. 1 J. Klotzbach No. 1 L. Tyler No. 1 Albert McClurg No. 1 Arthur N. Kennedy No. 1 Hubbard 

Permanent datum GL GL GL GL GL 

Ground level elevation (ft) 862 703 988.5 599 1,760 

Kelly bushing elevation (ft) 870 716 1,003 612 1,775 

Measured from KB KB KB KB KB 

Drill depth (ft) 3,950 4,000 5,648 6,387 10,061 

Formation 7 Clinton Group (Rochester Shale) Clinton Group (Reynales 

Limestone)

Geneseo Shale Member of the 

Genesee Formation

Geneseo Shale Member of the 

Genesee Formation

Cashaqua Shale Member of the 

Sonyea Formation

System or series: Silurian Silurian Upper Devonian Upper Devonian Upper Devonian 

Formation top (relative to KB) (ft) -675 -614 -128 -342 -1,845 

Formation top (relative to GL) (ft) -667 -601 -114 -329 -1,830 

Formation top (relative to SL) (ft) 195 102 875 270 -70 

Formation 8 Clinton Group (Irondequoit 

Limestone)

Clinton Group (lower unnamed 

shale)

Tully Limestone (unconformity) Tully Limestone (unconformity) Middlesex Shale Member of the 

Sonyea Formation

System or series: Silurian Silurian Middle Devonian Middle Devonian Upper Devonian 

Formation top (relative to KB) (ft) -788 -626 -167 -373 -2,002 

Formation top (relative to GL) (ft) -780 -613 -153 -360 -1,987 

Formation top (relative to SL) (ft) 82 90 836 239 -227 

Formation 9 Clinton Group (middle unnamed 

shale)

Medina Group (sandstone) Hamilton Group (Moscow Shale) Hamilton Group (Moscow Shale) West River Shale Member of the 

Genesee Formation1

System or series: Silurian Silurian Middle Devonian Middle Devonian Upper Devonian 

Formation top (relative to KB) (ft) -798 -630 -185 -377 -172 

Formation top (relative to GL) (ft) -790 -617 -171 -364 -157 

Formation top (relative to SL) (ft) 72 86 818 235 1,603 
Appendix 1. 33

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number

American Petroleum Institute 

well number

Lease name

Permanent datum

Ground level elevation (ft)

Kelly bushing elevation (ft)

Measured from

Drill depth (ft)

6

31–101–03924

No. 1 Robert Olin

GL

1,645

1,658

KB

13,508

7

37–117–20057

No. 1 Harry P. Dewey

GL

1,569

1,587

KB

15,082

8

37–105–20182

No. 1 Pa. Dept. of Forest and 

Water Tract 129

GL

1,847

1,870

KB

18,834

9

37–035–20276

No. 1 Pa. State Forest, 

Tract 285–1

GL

2,004

2,037

KB

19,360

10

37–081–90002

No. 1 W.E. Snyder

DF

726

726

KB

5,808

Formation 7 Onondaga Limestone Penn Yan Shale and Lodi 

Limestone Members (undivided) 

of the Genesee Formation1

West River Shale and 

Genundewa Limestone Members 

(undivided) of the Genesee 

Formation1

Brallier Formation (shale and 

siltstone)

Gatesburg Formation (Mines 

Dolomite Member)

System or series: Middle Devonian Upper Devonian Upper Devonian Upper Devonian Upper Cambrian

Formation top (relative to KB) (ft) -4,045 -4,474 -4,860 -4,787 -3,060

Formation top (relative to GL) (ft) -4,032 -4,456 -4,837 -4,754 -3,060

Formation top (relative to SL) (ft) -2,387 -2,887 -2,990 -2,750 -2,334

Formation 8 Oriskany Sandstone 

(unconformity)

Geneseo Shale Member of the 

Genesee Formation

Penn Yan Shale and Lodi 

Limestone Members (undivided) 

of the Genesee Formation1

Middlesex Shale Member of the 

Sonyea Formation

Gatesburg Formation (upper 

sandy member)

System or series: Lower Devonian Upper Devonian Upper Devonian Upper Devonian Upper Cambrian

Formation top (relative to KB) (ft) -4,080 -4,642 -5,290 -6,250 -3,300

Formation top (relative to GL) (ft) -4,067 -4,624 -5,267 -6,217 -3,300

Formation top (relative to SL) (ft) -2,422 -3,055 -3,420 -4,213 -2,574

Formation 9 Helderberg Group (limestone) 

(unconformity)

Tully Limestone (unconformity) Geneseo Shale Member of the 

Genesee Formation

West River Shale and 

Genundewa Limestone Members 

(undivided) of the Genesee 

Formation1

Gatesburg Formation (Ore Hill 

Member) (limestone)

System or series: Lower Devonian Middle Devonian Upper Devonian Upper Devonian Upper Cambrian

Formation top (relative to KB) (ft) -4,140 -4,764 -5,480 -6,492 -3,810

Formation top (relative to GL) (ft) -4,127 -4,746 -5,457 -6,459 -3,810

Formation top (relative to SL) (ft) -2,482 -3,177 -3,610 -4,455 -3,084
34 Geologic Cross Section A–A′ Through the Appalachian Basin

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number 1 2 3 4 5 

American Petroleum Institute 

well number 31–037–05117 31–037–04593 31–051–04552 31–051–04630 31–101–21496 

Lease name No. 1 J. Klotzbach No. 1 L. Tyler No. 1 Albert McClurg No. 1 Arthur N. Kennedy No. 1 Hubbard 

Permanent datum GL GL GL GL GL 

Ground level elevation (ft) 862 703 988.5 599 1,760 

Kelly bushing elevation (ft) 870 716 1,003 612 1,775 

Measured from KB KB KB KB KB 

Drill depth (ft) 3,950 4,000 5,648 6,387 10,061 

Formation 10 Clinton Group (Reynales 

Limestone)

Queenston Shale (Cherokee 

unconformity)

Hamilton Group (Tichenor 

Limestone Member of Moscow 

Shale)2

Hamilton Group (Tichenor 

Limestone Member of Moscow 

Shale)2

Genundewa Limestone Member 

of the Genesee Formation1

System or series: Silurian Upper Ordovician Middle Devonian Middle Devonian Upper Devonian 

Formation top (relative to KB) (ft) -802 -722 -306 -512 -2,340 

Formation top (relative to GL) (ft) -794 -709 -292 -499 -2,325 

Formation top (relative to SL) (ft) 68 -6 697 100 -565 

Formation 11 Clinton Group (lower unnamed 

shale)

Oswego Sandstone Hamilton Group (Ludlowville 

Shale)

Hamilton Group (Ludlowville 

Shale)

Penn Yan Shale Member of the 

Genesee Formation1

System or series: Silurian Upper Ordovician Middle Devonian Middle Devonian Upper Devonian 

Formation top (relative to KB) (ft) -811 -1,715 -314 -523 -2,347 

Formation top (relative to GL) (ft) -803 -1,702 -300 -510 -2,332 

Formation top (relative to SL) (ft) 59 -999 689 89 -572 

Formation 12 Medina Group (sandstone) Lorraine Shale Hamilton Group (Centerfield 

Limestone Member of 

Ludlowville Shale)2

Hamilton Group (Centerfield 

Limestone Member of 

Ludlowville Shale)2

Lodi Limestone Member of the 

Genesee Formation1

System or series: Silurian Upper Ordovician Middle Devonian Middle Devonian Upper Devonian 

Formation top (relative to KB) (ft) -820 -1,797 -429 -632 -2,500 

Formation top (relative to GL) (ft) -812 -1,784 -415 -619 -2,485 

Formation top (relative to SL) (ft) 50 -1,081 574 -20 -725 
Appendix 1. 35

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number

American Petroleum Institute 

well number

Lease name

Permanent datum

Ground level elevation (ft)

Kelly bushing elevation (ft)

Measured from

Drill depth (ft)

6

31–101–03924

No. 1 Robert Olin

GL

1,645

1,658

KB

13,508

7

37–117–20057

No. 1 Harry P. Dewey

GL

1,569

1,587

KB

15,082

8

37–105–20182

No. 1 Pa. Dept. of Forest and 

Water Tract 129

GL

1,847

1,870

KB

18,834

9

37–035–20276

No. 1 Pa. State Forest, 

Tract 285–1

GL

2,004

2,037

KB

19,360

10

37–081–90002

No. 1 W.E. Snyder

DF

726

726

KB

5,808

Formation 10 Salina Group (Camillus Shale) Hamilton Group (Moscow Shale) Tully Limestone (unconformity) Penn Yan Shale and Lodi 

Limestone Members (undivided) 

of the Genesee Formation1

Gatesburg Formation (lower 

sandy member)

System or series: upper Silurian Middle Devonian Middle Devonian Upper Devonian Upper Cambrian

Formation top (relative to KB) (ft) -4,368 -4,840 -5,550 -6,906 -3,950

Formation top (relative to GL) (ft) -4,355 -4,822 -5,527 -6,873 -3,950

Formation top (relative to SL) (ft) -2,710 -3,253 -3,680 -4,869 -3,224

Formation 11 Salina Group (Syracuse Salt) 

(anhydritic dolomite and shale)

Hamilton Group (Menteth 

Limestone Member of Moscow 

Shale)2

Hamilton Group (Moscow Shale) Geneseo Shale Member of the 

Genesee Formation 

Warrior Formation (limestone)

System or series: upper Silurian Middle Devonian Middle Devonian Upper Devonian Upper Cambrian

Formation top (relative to KB) (ft) -4,447 -4,940 -5,640 -7,066 -4,300

Formation top (relative to GL) (ft) -4,434 -4,922 -5,617 -7,033 -4,300

Formation top (relative to SL) (ft) -2,789 -3,353 -3,770 -5,029 -3,574

Formation 12 Salina Group (Syracuse Salt) 

(upper halite)

Hamilton Group (Deep Run 

Shale Member of Moscow 

Shale)2

Hamilton Group (Menteth 

Limestone Member of Moscow 

Shale)2

Tully Limestone (unconformity) Warrior Formation (sandy 

dolomite)

System or series: upper Silurian Middle Devonian Middle Devonian Middle Devonian Middle Cambrian

Formation top (relative to KB) (ft) -4,500 -4,952 -5,764 -7,150 -4,500

Formation top (relative to GL) (ft) -4,487 -4,934 -5,741 -7,117 -4,500

Formation top (relative to SL) (ft) -2,842 -3,365 -3,894 -5,113 -3,774
36 Geologic Cross Section A–A′ Through the Appalachian Basin

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number 1 2 3 4 5 

American Petroleum Institute 

well number 31–037–05117 31–037–04593 31–051–04552 31–051–04630 31–101–21496 

Lease name No. 1 J. Klotzbach No. 1 L. Tyler No. 1 Albert McClurg No. 1 Arthur N. Kennedy No. 1 Hubbard 

Permanent datum GL GL GL GL GL 

Ground level elevation (ft) 862 703 988.5 599 1,760 

Kelly bushing elevation (ft) 870 716 1,003 612 1,775 

Measured from KB KB KB KB KB 

Drill depth (ft) 3,950 4,000 5,648 6,387 10,061 

Formation 13 Queenston Shale (Cherokee 

unconformity)

Utica Shale Hamilton Group (Skaneateles 

Shale)

Hamilton Group (Skaneateles 

Shale)

Geneseo Shale Member of the 

Genesee Formation

System or series: Upper Ordovician Upper Ordovician Middle Devonian Middle Devonian Upper Devonian 

Formation top (relative to KB) (ft) -920 -2,300 -437 -641 -2,520 

Formation top (relative to GL) (ft) -912 -2,287 -423 -628 -2,505 

Formation top (relative to SL) (ft) -50 -1,584 566 -29 -745 

Formation 14 Oswego Sandstone Trenton Group (undivided) Hamilton Group (Stafford 

Limestone Member of the 

Skaneateles Shale)2

Hamilton Group (Stafford 

Limestone Member of the 

Skaneateles Shale)2

Tully Limestone (unconformity) 

System or series: Upper Ordovician Upper Ordovician Middle Devonian Middle Devonian Middle Devonian 

Formation top (relative to KB) (ft) -1,990 -2,458 -668 -894 -2,588 

Formation top (relative to GL) (ft) -1,982 -2,445 -654 -881 -2,573 

Formation top (relative to SL) (ft) -1,120 -1,742 335 -282 -813 

Formation 15 Lorraine Shale Trenton Group (Millbrig 

Bentonite Bed)

Hamilton Group (Marcellus 

Shale)

Hamilton Group (Marcellus 

Shale)

Hamilton Group (Moscow Shale) 

System or series: Upper Ordovician Upper Ordovician Middle Devonian Middle Devonian Middle Devonian 

Formation top (relative to KB) (ft) -2,076 -3,023 -673 -900 -2,620 

Formation top (relative to GL) (ft) -2,068 -3,010 -659 -887 -2,605 

Formation top (relative to SL) (ft) -1,206 -2,307 330 -288 -845 
Appendix 1. 37

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number

American Petroleum Institute 

well number

Lease name

Permanent datum

Ground level elevation (ft)

Kelly bushing elevation (ft)

Measured from

Drill depth (ft)

6

31–101–03924

No. 1 Robert Olin

GL

1,645

1,658

KB

13,508

7

37–117–20057

No. 1 Harry P. Dewey

GL

1,569

1,587

KB

15,082

8

37–105–20182

No. 1 Pa. Dept. of Forest and 

Water Tract 129

GL

1,847

1,870

KB

18,834

9

37–035–20276

No. 1 Pa. State Forest, 

Tract 285–1

GL

2,004

2,037

KB

19,360

10

37–081–90002

No. 1 W.E. Snyder

DF

726

726

KB

5,808

Formation 13 Salina Group (Syracuse Salt) 

(upper anhydritic dolomite)

Hamilton Group (Tichenor 

Limestone Member of Moscow 

Shale)2

Hamilton Group (Deep Run 

Shale Member of Moscow 

Shale)2

Hamilton Group (Moscow Shale) Warrior Formation (argillaceous 

limestone)

System or series: upper Silurian Middle Devonian Middle Devonian Middle Devonian Middle Cambrian

Formation top (relative to KB) (ft) -4,990 -4,998 -5,773 -7,310 -4,800

Formation top (relative to GL) (ft) -4,977 -4,980 -5,750 -7,277 -4,800

Formation top (relative to SL) (ft) -3,332 -3,411 -3,903 -5,273 -4,074

Formation 14 Salina Group (Syracuse Salt) 

(middle halite)

Hamilton Group (Ludlowville 

Shale)

Hamilton Group (Tichenor 

Limestone Member of Moscow 

Shale)2

Hamilton Group (Menteth 

Limestone Member of Moscow 

Shale)2

Warrior Formation (sandy 

dolomite)

System or series: upper Silurian Middle Devonian Middle Devonian Middle Devonian Middle Cambrian

Formation top (relative to KB) (ft) -5,130 -5,004 -5,780 -7,460 -5,200

Formation top (relative to GL) (ft) -5,117 -4,986 -5,757 -7,427 -5,200

Formation top (relative to SL) (ft) -3,472 -3,417 -3,910 -5,423 -4,474

Formation 15 Salina Group (Syracuse Salt) 

(lower anhydritic dolomite)

Hamilton Group (Centerfield 

Limestone Member of 

Ludlowville Shale)2

Hamilton Group (Ludlowville 

Shale)

Hamilton Group (Deep Run 

Shale Member of Moscow 

Shale)2

System or series: upper Silurian Middle Devonian Middle Devonian Middle Devonian

Formation top (relative to KB) (ft) -5,160 -5,268 -5,800 -7,469

Formation top (relative to GL) (ft) -5,147 -5,250 -5,777 -7,436

Formation top (relative to SL) (ft) -3,502 -3,681 -3,930 -5,432
38 Geologic Cross Section A–A′ Through the Appalachian Basin

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number 1 2 3 4 5 

American Petroleum Institute 

well number 31–037–05117 31–037–04593 31–051–04552 31–051–04630 31–101–21496 

Lease name No. 1 J. Klotzbach No. 1 L. Tyler No. 1 Albert McClurg No. 1 Arthur N. Kennedy No. 1 Hubbard 

Permanent datum GL GL GL GL GL 

Ground level elevation (ft) 862 703 988.5 599 1,760 

Kelly bushing elevation (ft) 870 716 1,003 612 1,775 

Measured from KB KB KB KB KB 

Drill depth (ft) 3,950 4,000 5,648 6,387 10,061 

Formation 16 Utica Shale Trenton Group (Deicke 

Bentonite Bed)

Onondaga Limestone Onondaga Limestone Hamilton Group (Menteth 

Limestone Member of Moscow 

Shale)2

System or series: Upper Ordovician Upper Ordovician Middle Devonian Middle Devonian Middle Devonian 

Formation top (relative to KB) (ft) -2,563 -3,048 -699 -940 -2,713 

Formation top (relative to GL) (ft) -2,555 -3,035 -685 -927 -2,698 

Formation top (relative to SL) (ft) -1,693 -2,332 304 -328 -938 

Formation 17 Trenton Group (undivided) Black River Group (undivided) Akron Dolomite (unconformity) Oriskany Sandstone 

(unconformity)

Hamilton Group (Deep Run 

Shale Member of Moscow 

Shale)2

System or series: Upper Ordovician Middle and Upper Ordovician upper Silurian Lower Devonian Middle Devonian 

Formation top (relative to KB) (ft) -2,712 -3,122 -838 -1,040 -2,720 

Formation top (relative to GL) (ft) -2,704 -3,109 -824 -1,027 -2,705 

Formation top (relative to SL) (ft) -1,842 -2,406 165 -428 -945 

Formation 18 Trenton Group (Millbrig 

Bentonite Bed)

Black River Group (marker x) Salina Group (Bertie Dolomite) 

(anhydritic)

Akron Dolomite (unconformity) Hamilton Group (Tichenor 

Limestone Member of Moscow 

Shale)2

System or series: Upper Ordovician Middle and Upper Ordovician upper Silurian upper Silurian Middle Devonian 

Formation top (relative to KB) (ft) -3,141 -3,300 -905 -1,055 -2,778 

Formation top (relative to GL) (ft) -3,133 -3,287 -891 -1,042 -2,763 

Formation top (relative to SL) (ft) -2,271 -2,584 98 -443 -1,003 
Appendix 1. 39

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number

American Petroleum Institute 

well number

Lease name

Permanent datum

Ground level elevation (ft)

Kelly bushing elevation (ft)

Measured from

Drill depth (ft)

6

31–101–03924

No. 1 Robert Olin

GL

1,645

1,658

KB

13,508

7

37–117–20057

No. 1 Harry P. Dewey

GL

1,569

1,587

KB

15,082

8

37–105–20182

No. 1 Pa. Dept. of Forest and 

Water Tract 129

GL

1,847

1,870

KB

18,834

9

37–035–20276

No. 1 Pa. State Forest, 

Tract 285–1

GL

2,004

2,037

KB

19,360

10

37–081–90002

No. 1 W.E. Snyder

DF

726

726

KB

5,808

Formation 16 Salina Group (Syracuse Salt) 

(lower halite)

Hamilton Group (Skaneateles 

Shale)

Hamilton Group (Centerfield 

Limestone Member of 

Ludlowville Shale)2

Hamilton Group (Tichenor 

Limestone Member of Moscow 

Shale)2

System or series: upper Silurian Middle Devonian Middle Devonian Middle Devonian

Formation top (relative to KB) (ft) -5,380 -5,280 -6,070 -7,490

Formation top (relative to GL) (ft) -5,367 -5,262 -6,047 -7,457

Formation top (relative to SL) (ft) -3,722 -3,693 -4,200 -5,453

Formation 17 Salina Group (Vernon Shale) 

(green shale and anhydritic 

dolomite)

Hamilton Group (Stafford 

Limestone Member of the 

Skaneateles Shale)2

Hamilton Group (Skaneateles 

Shale)

Hamilton Group (Ludlowville 

Shale)

System or series: upper Silurian Middle Devonian Middle Devonian Middle Devonian

Formation top (relative to KB) (ft) -5,462 -5,504 -6,076 -7,510

Formation top (relative to GL) (ft) -5,449 -5,486 -6,053 -7,477

Formation top (relative to SL) (ft) -3,804 -3,917 -4,206 -5,473

Formation 18 Lockport Group (dolomite) Hamilton Group (upper unnamed 

shale member of the Marcellus 

Shale)2

Hamilton Group (Stafford 

Limestone Member of the 

Skaneateles Shale)2

Hamilton Group (Centerfield 

Limestone Member of 

Ludlowville Shale)2

System or series: lower and upper Silurian Middle Devonian Middle Devonian Middle Devonian

Formation top (relative to KB) (ft) -6,378 -5,520 -6,203 -7,740

Formation top (relative to GL) (ft) -6,365 -5,502 -6,180 -7,707

Formation top (relative to SL) (ft) -4,720 -3,933 -4,333 -5,703
40 Geologic Cross Section A–A′ Through the Appalachian Basin

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number 1 2 3 4 5 

American Petroleum Institute 

well number 31–037–05117 31–037–04593 31–051–04552 31–051–04630 31–101–21496 

Lease name No. 1 J. Klotzbach No. 1 L. Tyler No. 1 Albert McClurg No. 1 Arthur N. Kennedy No. 1 Hubbard 

Permanent datum GL GL GL GL GL 

Ground level elevation (ft) 862 703 988.5 599 1,760 

Kelly bushing elevation (ft) 870 716 1,003 612 1,775 

Measured from KB KB KB KB KB 

Drill depth (ft) 3,950 4,000 5,648 6,387 10,061 

Formation 19 Trenton Group (Deicke 

Bentonite Bed)

Black River Group (marker y) Salina Group (Camillus Shale) Salina Group (Bertie Dolomite) 

(anhydritic)

Hamilton Group (Ludlowville 

Shale)

System or series: Upper Ordovician Middle and Upper Ordovician upper Silurian upper Silurian Middle Devonian 

Formation top (relative to KB) (ft) -3,174 -3,376 -913 -1,152 -2,800 

Formation top (relative to GL) (ft) -3,166 -3,363 -899 -1,139 -2,785 

Formation top (relative to SL) (ft) -2,304 -2,660 90 -540 -1,025 

Formation 20 Black River Group (undivided) Black River Group (argillaceous 

limestone and dolomite)

Salina Group (Syracuse Salt) 

(anhydritic dolomite and shale)

Salina Group (Camillus Shale) Hamilton Group (Centerfield 

Limestone Member of 

Ludlowville Shale)2

System or series: Middle and Upper Ordovician Middle and Upper Ordovician upper Silurian upper Silurian Middle Devonian 

Formation top (relative to KB) (ft) -3,240 -3,426 -974 -1,195 -2,922 

Formation top (relative to GL) (ft) -3,232 -3,413 -960 -1,182 -2,907 

Formation top (relative to SL) (ft) -2,370 -2,710 29 -583 -1,147 

Formation 21 Black River Group (marker x) Galway Formation (upper 

dolomite) (Knox unconformity)

Salina Group (Syracuse Salt) 

(anhydritic shale and dolomite)

Salina Group (Syracuse Salt) 

(anhydritic dolomite and shale)

Hamilton Group (Skaneateles 

Shale)

System or series: Middle and Upper Ordovician Upper Cambrian upper Silurian upper Silurian Middle Devonian 

Formation top (relative to KB) (ft) -3,355 -3,520 -1,155 -1,260 -2,930 

Formation top (relative to GL) (ft) -3,347 -3,507 -1,141 -1,247 -2,915 

Formation top (relative to SL) (ft) -2,485 -2,804 -153 -648 -1,155 
Appendix 1. 41

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number

American Petroleum Institute 

well number

Lease name

Permanent datum

Ground level elevation (ft)

Kelly bushing elevation (ft)

Measured from

Drill depth (ft)

6

31–101–03924

No. 1 Robert Olin

GL

1,645

1,658

KB

13,508

7

37–117–20057

No. 1 Harry P. Dewey

GL

1,569

1,587

KB

15,082

8

37–105–20182

No. 1 Pa. Dept. of Forest and 

Water Tract 129

GL

1,847

1,870

KB

18,834

9

37–035–20276

No. 1 Pa. State Forest, 

Tract 285–1

GL

2,004

2,037

KB

19,360

10

37–081–90002

No. 1 W.E. Snyder

DF

726

726

KB

5,808

Formation 19 Clinton Group (Rochester Shale) Hamilton Group (Purcell 

Limestone Member of the 

Marcellus Shale)2

Hamilton Group (upper unnamed 

shale member of the Marcellus 

Shale)2

Hamilton Group (Skaneateles 

Shale)

System or series: Silurian Middle Devonian Middle Devonian Middle Devonian

Formation top (relative to KB) (ft) -6,535 -5,544 -6,238 -7,748

Formation top (relative to GL) (ft) -6,522 -5,526 -6,215 -7,715

Formation top (relative to SL) (ft) -4,877 -3,957 -4,368 -5,711

Formation 20 Clinton Group (Irondequoit 

Limestone)

Hamilton Group (middle 

unnamed shale member of the 

Marcellus Shale)2

Hamilton Group (Purcell 

Limestone Member of the 

Marcellus Shale)2

Hamilton Group (Stafford 

Limestone Member of the 

Skaneateles Shale)2

System or series: Silurian Middle Devonian Middle Devonian Middle Devonian

Formation top (relative to KB) (ft) -6,710 -5,550 -6,259 -7,940

Formation top (relative to GL) (ft) -6,697 -5,532 -6,236 -7,907

Formation top (relative to SL) (ft) -5,052 -3,963 -4,389 -5,903

Formation 21 Clinton Group (middle unnamed 

shale)

Hamilton Group (Cherry Valley 

Limestone Member of the 

Marcellus Shale)2

Hamilton Group (middle 

unnamed shale member of the 

Marcellus Shale)2

Hamilton Group (upper unnamed 

shale member of the Marcellus 

Shale)2

System or series: Silurian Middle Devonian Middle Devonian Middle Devonian

Formation top (relative to KB) (ft) -6,735 -5,560 -6,267 -8,000

Formation top (relative to GL) (ft) -6,722 -5,542 -6,244 -7,967

Formation top (relative to SL) (ft) -5,077 -3,973 -4,397 -5,963
42 Geologic Cross Section A–A′ Through the Appalachian Basin

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number 1 2 3 4 5 

American Petroleum Institute 

well number 31–037–05117 31–037–04593 31–051–04552 31–051–04630 31–101–21496 

Lease name No. 1 J. Klotzbach No. 1 L. Tyler No. 1 Albert McClurg No. 1 Arthur N. Kennedy No. 1 Hubbard 

Permanent datum GL GL GL GL GL 

Ground level elevation (ft) 862 703 988.5 599 1,760 

Kelly bushing elevation (ft) 870 716 1,003 612 1,775 

Measured from KB KB KB KB KB 

Drill depth (ft) 3,950 4,000 5,648 6,387 10,061 

Formation 22 Black River Group (marker y) granite and (or) gneiss Salina Group (Syracuse Salt) 

(anhydritic dolomite and shale)

Salina Group (Syracuse Salt) 

(upper halite)

Hamilton Group (Stafford 

Limestone Member of the 

Skaneateles Shale)2

System or series: Middle and Upper Ordovician Mesoproterozoic upper Silurian upper Silurian Middle Devonian 

Formation top (relative to KB) (ft) -3,419 -3,812 -1,278 -1,565 -3,192 

Formation top (relative to GL) (ft) -3,411 -3,799 -1,264 -1,552 -3,177 

Formation top (relative to SL) (ft) -2,549 -3,096 -276 -953 -1,417 

Formation 23 Black River Group (argillaceous 

limestone and dolomite)

Salina Group (Syracuse Salt) 

(halite)

Salina Group (Syracuse Salt) 

(anhydritic dolomite and shale)

Hamilton Group (Marcellus 

Shale)

System or series: Middle and Upper Ordovician upper Silurian upper Silurian Middle Devonian 

Formation top (relative to KB) (ft) -3,470 -1,355 -1,635 -3,210 

Formation top (relative to GL) (ft) -3,462 -1,341 -1,622 -3,195 

Formation top (relative to SL) (ft) -2,600 -353 -1,023 -1,435 

Formation 24 Galway Formation (upper 

dolomite) (Knox unconformity)

Salina Group (Syracuse Salt) 

(lower halite)

Salina Group (Syracuse Salt) 

(lower halite)

Onondaga Limestone 

System or series: Upper Cambrian upper Silurian upper Silurian Middle Devonian 

Formation top (relative to KB) (ft) -3,555 -1,825 -1,825 -3,260 

Formation top (relative to GL) (ft) -3,547 -1,812 -1,812 -3,245 

Formation top (relative to SL) (ft) -2,685 -1,213 -1,213 -1,485 
Appendix 1. 43

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number

American Petroleum Institute 

well number

Lease name

Permanent datum

Ground level elevation (ft)

Kelly bushing elevation (ft)

Measured from

Drill depth (ft)

6

31–101–03924

No. 1 Robert Olin

GL

1,645

1,658

KB

13,508

7

37–117–20057

No. 1 Harry P. Dewey

GL

1,569

1,587

KB

15,082

8

37–105–20182

No. 1 Pa. Dept. of Forest and 

Water Tract 129

GL

1,847

1,870

KB

18,834

9

37–035–20276

No. 1 Pa. State Forest, 

Tract 285–1

GL

2,004

2,037

KB

19,360

10

37–081–90002

No. 1 W.E. Snyder

DF

726

726

KB

5,808

Formation 22 Clinton Group (Reynales 

Limestone)

Hamilton Group (lower unnamed 

shale member of the Marcellus 

Shale)2

Hamilton Group (Cherry Valley 

Limestone Member of the 

Marcellus Shale)2

Hamilton Group (Purcell 

Limestone Member of the 

Marcellus Shale)2

System or series: Silurian Middle Devonian Middle Devonian Middle Devonian

Formation top (relative to KB) (ft) -6,865 -5,564 -6,293 -8,020

Formation top (relative to GL) (ft) -6,852 -5,546 -6,270 -7,987

Formation top (relative to SL) (ft) -5,207 -3,977 -4,423 -5,983

Formation 23 Clinton Group (lower unnamed 

shale)

Onondaga Limestone Hamilton Group (lower unnamed 

shale member of the Marcellus 

Shale)2

Hamilton Group (middle 

unnamed shale member of the 

Marcellus Shale)2

System or series: Silurian Middle Devonian Middle Devonian Middle Devonian

Formation top (relative to KB) (ft) -6,900 -5,626 -6,300 -8,050

Formation top (relative to GL) (ft) -6,887 -5,608 -6,277 -8,017

Formation top (relative to SL) (ft) -5,242 -4,039 -4,430 -6,013

Formation 24 Medina Group (Cambria 

Shale and Thorold Sandstone) 

(undivided)

Oriskany Sandstone 

(unconformity)

Tioga bentonite bed Hamilton Group (Cherry Valley 

Limestone Member of the 

Marcellus Shale)2

System or series: Silurian Lower Devonian Middle Devonian Middle Devonian

Formation top (relative to KB) (ft) -6,972 -5,646 -6,355 -8,089

Formation top (relative to GL) (ft) -6,959 -5,628 -6,332 -8,056

Formation top (relative to SL) (ft) -5,314 -4,059 -4,485 -6,052
44 Geologic Cross Section A–A′ Through the Appalachian Basin

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number 1 2 3 4 5 

American Petroleum Institute 

well number 31–037–05117 31–037–04593 31–051–04552 31–051–04630 31–101–21496 

Lease name No. 1 J. Klotzbach No. 1 L. Tyler No. 1 Albert McClurg No. 1 Arthur N. Kennedy No. 1 Hubbard 

Permanent datum GL GL GL GL GL 

Ground level elevation (ft) 862 703 988.5 599 1,760 

Kelly bushing elevation (ft) 870 716 1,003 612 1,775 

Measured from KB KB KB KB KB 

Drill depth (ft) 3,950 4,000 5,648 6,387 10,061 

Formation 25 Galway Formation (upper 

sandstone)

Salina Group (Vernon Shale) 

(green shale and anhydritic 

dolomite)

Salina Group (Vernon Shale) 

(green shale and anhydritic 

dolomite)

Helderberg Group (limestone) 

(unconformity)

System or series: Upper Cambrian upper Silurian upper Silurian Lower Devonian 

Formation top (relative to KB) (ft) -3,700 -1,418 -1,900 -3,300 

Formation top (relative to GL) (ft) -3,692 -1,404 -1,887 -3,285 

Formation top (relative to SL) (ft) -2,830 -416 -1,288 -1,525 

Formation 26 Galway Formation (middle 

dolomite)

Lockport Group (dolomite) Lockport Group (dolomite) Salina Group (Camillus Shale) 

System or series: Upper Cambrian lower and upper Silurian lower and upper Silurian upper Silurian 

Formation top (relative to KB) (ft) -3,740 -1,548 -2,058 -3,468 

Formation top (relative to GL) (ft) -3,732 -1,534 -2,045 -3,453 

Formation top (relative to SL) (ft) -2,870 -546 -1,446 -1,693 

Formation 27 Galway Formation (lower 

sandstone)

Clinton Group (Rochester Shale) Clinton Group (Rochester Shale) Salina Group (Syracuse Salt) 

(halite)

System or series: Upper Cambrian Silurian Silurian upper Silurian 

Formation top (relative to KB) (ft) -3,810 -1,680 -2,255 -3,542 

Formation top (relative to GL) (ft) -3,802 -1,666 -2,242 -3,527 

Formation top (relative to SL) (ft) -2,940 -678 -1,643 -1,767 
Appendix 1. 45

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number

American Petroleum Institute 

well number

Lease name

Permanent datum

Ground level elevation (ft)

Kelly bushing elevation (ft)

Measured from

Drill depth (ft)

6

31–101–03924

No. 1 Robert Olin

GL

1,645

1,658

KB

13,508

7

37–117–20057

No. 1 Harry P. Dewey

GL

1,569

1,587

KB

15,082

8

37–105–20182

No. 1 Pa. Dept. of Forest and 

Water Tract 129

GL

1,847

1,870

KB

18,834

9

37–035–20276

No. 1 Pa. State Forest, 

Tract 285–1

GL

2,004

2,037

KB

19,360

10

37–081–90002

No. 1 W.E. Snyder

DF

726

726

KB

5,808

Formation 25 Medina Group (Grimsby 

Sandstone and Whirlpool 

Sandstone) (undivided)

Shriver Chert, Mandata Sh., 

Corriganville Ls., New Creek 

Ls., and Keyser Fm. (undivided) 

(unconformity)

Onondaga Limestone Hamilton Group (lower unnamed 

shale member of the Marcellus 

Shale)2

System or series: Silurian Lower Devonian Middle Devonian Middle Devonian

Formation top (relative to KB) (ft) -7,107 -5,672 -6,365 -8,092

Formation top (relative to GL) (ft) -7,094 -5,654 -6,342 -8,059

Formation top (relative to SL) (ft) -5,449 -4,085 -4,495 -6,055

Formation 26 Queenston Shale (Cherokee 

unconformity)

Salina Group (Bertie Limestone) 

(anhydritic dolomite)

Oriskany Sandstone 

(unconformity)

Tioga bentonite bed

System or series: Upper Ordovician upper Silurian Lower Devonian Middle Devonian

Formation top (relative to KB) (ft) -7,175 -5,840 -6,380 -8,179

Formation top (relative to GL) (ft) -7,162 -5,822 -6,357 -8,146

Formation top (relative to SL) (ft) -5,517 -4,253 -4,510 -6,142

Formation 27 Oswego Sandstone Salina Group (Camillus Shale) Shriver Chert, Mandata Sh., 

Corriganville Ls., New Creek 

Ls., and Keyser Fm. (uppermost 

part) (undivided) (unconformity)

Onondaga Limestone

System or series: Upper Ordovician upper Silurian Lower Devonian Middle Devonian

Formation top (relative to KB) (ft) -8,130 -6,028 -6,410 -8,181

Formation top (relative to GL) (ft) -8,117 -6,010 -6,387 -8,148

Formation top (relative to SL) (ft) -6,472 -4,441 -4,540 -6,144
46 Geologic Cross Section A–A′ Through the Appalachian Basin

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number 1 2 3 4 5 

American Petroleum Institute 

well number 31–037–05117 31–037–04593 31–051–04552 31–051–04630 31–101–21496 

Lease name No. 1 J. Klotzbach No. 1 L. Tyler No. 1 Albert McClurg No. 1 Arthur N. Kennedy No. 1 Hubbard 

Permanent datum GL GL GL GL GL 

Ground level elevation (ft) 862 703 988.5 599 1,760 

Kelly bushing elevation (ft) 870 716 1,003 612 1,775 

Measured from KB KB KB KB KB 

Drill depth (ft) 3,950 4,000 5,648 6,387 10,061 

Formation 28 Galway Formation (lower 

dolomite)

Clinton Group (Irondequoit 

Limestone)

Clinton Group (Irondequoit 

Limestone)

Salina Group (Vernon Shale) 

(green shale and anhydritic 

dolomite)

System or series: Upper Cambrian Silurian Silurian upper Silurian 

Formation top (relative to KB) (ft) -3,855 -1,868 -2,400 -4,404 

Formation top (relative to GL) (ft) -3,847 -1,854 -2,387 -4,389 

Formation top (relative to SL) (ft) -2,985 -866 -1,788 -2,629 

Formation 29 granite and (or) gneiss Clinton Group (middle unnamed 

shale)

Clinton Group (middle unnamed 

shale)

Lockport Group (dolomite) 

System or series: Mesoproterozoic Silurian Silurian lower and upper Silurian 

Formation top (relative to KB) (ft) -3,895 -1,874 -2,408 -4,744 

Formation top (relative to GL) (ft) -3,887 -1,860 -2,395 -4,729 

Formation top (relative to SL) (ft) -3,025 -872 -1,796 -2,969 

Formation 30 Clinton Group (Reynales 

Limestone and lower unnamed 

shale) (undivided)

Clinton Group (Reynales 

Limestone and lower unnamed 

shale) (undivided)

Clinton Group (Rochester Shale) 

System or series: Silurian Silurian Silurian 

Formation top (relative to KB) (ft) -1,895 -2,439 -4,957 

Formation top (relative to GL) (ft) -1,881 -2,426 -4,942 

Formation top (relative to SL) (ft) -893 -1,827 -3,182 
Appendix 1. 47

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number

American Petroleum Institute 

well number

Lease name

Permanent datum

Ground level elevation (ft)

Kelly bushing elevation (ft)

Measured from

Drill depth (ft)

6

31–101–03924

No. 1 Robert Olin

GL

1,645

1,658

KB

13,508

7

37–117–20057

No. 1 Harry P. Dewey

GL

1,569

1,587

KB

15,082

8

37–105–20182

No. 1 Pa. Dept. of Forest and 

Water Tract 129

GL

1,847

1,870

KB

18,834

9

37–035–20276

No. 1 Pa. State Forest, 

Tract 285–1

GL

2,004

2,037

KB

19,360

10

37–081–90002

No. 1 W.E. Snyder

DF

726

726

KB

5,808

Formation 28 Lorraine Shale Salina Group (Syracuse Salt) 

(halite)

Keyser Formation (limestone) Oriskany Sandstone 

(unconformity)

System or series: Upper Ordovician upper Silurian Lower Devonian Lower Devonian

Formation top (relative to KB) (ft) -8,778 -6,104 -6,572 -8,231

Formation top (relative to GL) (ft) -8,765 -6,086 -6,549 -8,198

Formation top (relative to SL) (ft) -7,120 -4,517 -4,702 -6,194

Formation 29 Utica Shale Salina Group (Vernon Shale) 

(green shale and anhydritic 

dolomite)

Salina Group (Bertie Dolomite) 

(dolomite and shale)

Shriver Chert, Mandata Sh., 

Corriganville Ls., New Creek 

Ls., and Keyser Fm. (uppermost 

part) (undivided) (unconformity)

System or series: Upper Ordovician upper Silurian upper Silurian Lower Devonian

Formation top (relative to KB) (ft) -9,573 -7,220 -6,650 -8,280

Formation top (relative to GL) (ft) -9,560 -7,202 -6,627 -8,247

Formation top (relative to SL) (ft) -7,915 -5,633 -4,780 -6,243

Formation 30 Trenton Group (undivided) Bloomsburg Formation (red 

shale)

Salina Group (Camillus Shale) Keyser Formation

System or series: Upper Ordovician upper Silurian upper Silurian Lower Devonian

Formation top (relative to KB) (ft) -9,672 -7,638 -6,772 -8,430

Formation top (relative to GL) (ft) -9,659 -7,620 -6,749 -8,397

Formation top (relative to SL) (ft) -8,014 -6,051 -4,902 -6,393
48 Geologic Cross Section A–A′ Through the Appalachian Basin

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number 1 2 3 4 5 

American Petroleum Institute 

well number 31–037–05117 31–037–04593 31–051–04552 31–051–04630 31–101–21496 

Lease name No. 1 J. Klotzbach No. 1 L. Tyler No. 1 Albert McClurg No. 1 Arthur N. Kennedy No. 1 Hubbard 

Permanent datum GL GL GL GL GL 

Ground level elevation (ft) 862 703 988.5 599 1,760 

Kelly bushing elevation (ft) 870 716 1,003 612 1,775 

Measured from KB KB KB KB KB 

Drill depth (ft) 3,950 4,000 5,648 6,387 10,061 

Formation 31 Medina Group (Cambria 

Shale and Thorold Sandstone) 

(undivided)

Medina Group (Cambria 

Shale and Thorold Sandstone) 

(undivided)

Clinton Group (Irondequoit 

Limestone)

System or series: Silurian Silurian Silurian 

Formation top (relative to KB) (ft) -1,900 -2,450 -5,048 

Formation top (relative to GL) (ft) -1,886 -2,437 -5,033 

Formation top (relative to SL) (ft) -898 -1,838 -3,273 

Formation 32 Medina Group (Grimsby 

Sandstone)

Medina Group (Grimsby 

Sandstone)

Clinton Group (middle unnamed 

shale)

System or series: Silurian Silurian Silurian 

Formation top (relative to KB) (ft) -1,940 -2,500 -5,068 

Formation top (relative to GL) (ft) -1,926 -2,487 -5,053 

Formation top (relative to SL) (ft) -938 -1,888 -3,293 

Formation 33 Queenston Shale (Cherokee 

unconformity)

Medina Group (Whirlpool 

Sandstone)

Clinton Group (Reynales 

Limestone and lower unnamed 

shale) (undivided)

System or series: Upper Ordovician Silurian Silurian 

Formation top (relative to KB) (ft) -2,003 -2,560 -5,116 

Formation top (relative to GL) (ft) -1,989 -2,547 -5,101 

Formation top (relative to SL) (ft) -1,001 -1,948 -3,341 
Appendix 1. 49

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number

American Petroleum Institute 

well number

Lease name

Permanent datum

Ground level elevation (ft)

Kelly bushing elevation (ft)

Measured from

Drill depth (ft)

6

31–101–03924

No. 1 Robert Olin

GL

1,645

1,658

KB

13,508

7

37–117–20057

No. 1 Harry P. Dewey

GL

1,569

1,587

KB

15,082

8

37–105–20182

No. 1 Pa. Dept. of Forest and 

Water Tract 129

GL

1,847

1,870

KB

18,834

9

37–035–20276

No. 1 Pa. State Forest, 

Tract 285–1

GL

2,004

2,037

KB

19,360

10

37–081–90002

No. 1 W.E. Snyder

DF

726

726

KB

5,808

Formation 31 Trenton Group (Millbrig 

Bentonite Bed)

Mifflintown Formation 

(McKenzie Member)

Salina Group (Syracuse Salt) 

(upper halite)

Salina Group (Bertie Limestone) 

(anhydritic dolomite)

System or series: Upper Ordovician Silurian upper Silurian upper Silurian

Formation top (relative to KB) (ft) -10,165 -7,922 -6,835 -8,520

Formation top (relative to GL) (ft) -10,152 -7,904 -6,812 -8,487

Formation top (relative to SL) (ft) -8,507 -6,335 -4,965 -6,483

Formation 32 Trenton Group (Deicke 

Bentonite Bed)

Clinton Group (Rochester Shale) Salina Group (Syracuse Salt) 

(upper anhydritic dolomite)

Salina Group (Camillus Shale)

System or series: Upper Ordovician Silurian upper Silurian upper Silurian

Formation top (relative to KB) (ft) -10,214 -8,170 -7,837 -8,663

Formation top (relative to GL) (ft) -10,201 -8,152 -7,814 -8,630

Formation top (relative to SL) (ft) -8,556 -6,583 -5,967 -6,626

Formation 33 Trenton Group (unnamed 

bentonite bed)

Clinton Group (Irondequoit 

Limestone) (equivalent to Keefer 

Formation of Pa.)

Salina Group (Syracuse Salt) 

(middle halite)

Salina Group (Syracuse Salt) 

(anhydritic dolomite and shale)

System or series: Upper Ordovician Silurian upper Silurian upper Silurian

Formation top (relative to KB) (ft) -10,230 -8,234 -8,041 -8,726

Formation top (relative to GL) (ft) -10,217 -8,216 -8,018 -8,693

Formation top (relative to SL) (ft) -8,572 -6,647 -6,171 -6,689
50 Geologic Cross Section A–A′ Through the Appalachian Basin

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number 1 2 3 4 5 

American Petroleum Institute 

well number 31–037–05117 31–037–04593 31–051–04552 31–051–04630 31–101–21496 

Lease name No. 1 J. Klotzbach No. 1 L. Tyler No. 1 Albert McClurg No. 1 Arthur N. Kennedy No. 1 Hubbard 

Permanent datum GL GL GL GL GL 

Ground level elevation (ft) 862 703 988.5 599 1,760 

Kelly bushing elevation (ft) 870 716 1,003 612 1,775 

Measured from KB KB KB KB KB 

Drill depth (ft) 3,950 4,000 5,648 6,387 10,061 

Formation 34 Oswego Sandstone Queenston Shale (Cherokee 

unconformity)

Medina Group (Cambria 

Shale and Thorold Sandstone) 

(undivided)

System or series: Upper Ordovician Upper Ordovician Silurian 

Formation top (relative to KB) (ft) -3,040 -2,572 -5,158 

Formation top (relative to GL) (ft) -3,026 -2,559 -5,143 

Formation top (relative to SL) (ft) -2,038 -1,960 -3,383 

Formation 35 Lorraine Shale Oswego Sandstone Medina Group (Grimsby 

Sandstone and Whirlpool 

Sandstone) (undivided)

System or series: Upper Ordovician Upper Ordovician Silurian 

Formation top (relative to KB) (ft) -3,133 -3,570 -5,219 

Formation top (relative to GL) (ft) -3,119 -3,557 -5,204 

Formation top (relative to SL) (ft) -2,131 -2,958 -3,444 

Formation 36 Utica Shale Lorraine Shale Queenston Shale (Cherokee 

unconformity)

System or series: Upper Ordovician Upper Ordovician Upper Ordovician 

Formation top (relative to KB) (ft) -3,675 -3,770 -5,290 

Formation top (relative to GL) (ft) -3,661 -3,757 -5,275 

Formation top (relative to SL) (ft) -2,673 -3,158 -3,515 
Appendix 1. 51

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number

American Petroleum Institute 

well number

Lease name

Permanent datum

Ground level elevation (ft)

Kelly bushing elevation (ft)

Measured from

Drill depth (ft)

6

31–101–03924

No. 1 Robert Olin

GL

1,645

1,658

KB

13,508

7

37–117–20057

No. 1 Harry P. Dewey

GL

1,569

1,587

KB

15,082

8

37–105–20182

No. 1 Pa. Dept. of Forest and 

Water Tract 129

GL

1,847

1,870

KB

18,834

9

37–035–20276

No. 1 Pa. State Forest, 

Tract 285–1

GL

2,004

2,037

KB

19,360

10

37–081–90002

No. 1 W.E. Snyder

DF

726

726

KB

5,808

Formation 34 Black River Group (undivided) Rose Hill Formation (upper shale 

member)

Salina Group (Syracuse Salt) 

(lower anhydritic dolomite)

Salina Group (Syracuse Salt) 

(halite)

System or series: Middle and Upper Ordovician lower Silurian upper Silurian upper Silurian

Formation top (relative to KB) (ft) -10,255 -8,250 -8,145 -8,942

Formation top (relative to GL) (ft) -10,242 -8,232 -8,122 -8,909

Formation top (relative to SL) (ft) -8,597 -6,663 -6,275 -6,905

Formation 35 Black River Group (marker x) Rose Hill Formation (upper 

limestone member) (equivalent 

to Reynales Limestone)

Salina Group (Syracuse Salt) 

(lower halite)

Wills Creek Formation 

(argillaceous dolomite with 

anhydrite) 

System or series: Middle and Upper Ordovician lower Silurian upper Silurian lower and upper Silurian

Formation top (relative to KB) (ft) -10,542 -8,424 -8,340 -9,543

Formation top (relative to GL) (ft) -10,529 -8,406 -8,317 -9,510

Formation top (relative to SL) (ft) -8,884 -6,837 -6,470 -7,506

Formation 36 Black River Group (marker y) Rose Hill Formation (lower shale 

member)

Wills Creek Formation 

(argillaceous dolomite with 

anhydrite) 

Bloomsburg Formation (red 

shale)

System or series: Middle and Upper Ordovician lower Silurian lower and upper Silurian upper Silurian

Formation top (relative to KB) (ft) -10,640 -8,433 -8,516 -10,005

Formation top (relative to GL) (ft) -10,627 -8,415 -8,493 -9,972

Formation top (relative to SL) (ft) -8,982 -6,846 -6,646 -7,968
52 Geologic Cross Section A–A′ Through the Appalachian Basin

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number 1 2 3 4 5 

American Petroleum Institute 

well number 31–037–05117 31–037–04593 31–051–04552 31–051–04630 31–101–21496 

Lease name No. 1 J. Klotzbach No. 1 L. Tyler No. 1 Albert McClurg No. 1 Arthur N. Kennedy No. 1 Hubbard 

Permanent datum GL GL GL GL GL 

Ground level elevation (ft) 862 703 988.5 599 1,760 

Kelly bushing elevation (ft) 870 716 1,003 612 1,775 

Measured from KB KB KB KB KB 

Drill depth (ft) 3,950 4,000 5,648 6,387 10,061 

Formation 37 Trenton Group (undivided) Utica Shale Oswego Sandstone 

System or series: Upper Ordovician Upper Ordovician Upper Ordovician 

Formation top (relative to KB) (ft) -3,855 -4,303 -6,070 

Formation top (relative to GL) (ft) -3,841 -4,290 -6,055 

Formation top (relative to SL) (ft) -2,853 -3,691 -4,295 

Formation 38 Trenton Group (Millbrig 

Bentonite Bed)

Trenton Group (undivided) Lorraine Shale 

System or series: Upper Ordovician Upper Ordovician Upper Ordovician 

Formation top (relative to KB) (ft) -4,431 -4,480 -6,262 

Formation top (relative to GL) (ft) -4,417 -4,467 -6,247 

Formation top (relative to SL) (ft) -3,429 -3,868 -4,487 

Formation 39 Trenton Group (Deicke 

Bentonite Bed)

Trenton Group (Millbrig 

Bentonite Bed)

Utica Shale 

System or series: Upper Ordovician Upper Ordovician Upper Ordovician 

Formation top (relative to KB) (ft) -4,457 -5,033 -6,900 

Formation top (relative to GL) (ft) -4,443 -5,020 -6,885 

Formation top (relative to SL) (ft) -3,455 -4,421 -5,125 

Formation 40 Black River Group (unnamed 

bentonite bed)

Trenton Group (Deicke 

Bentonite Bed)

Trenton Group (undivided) 

System or series: Middle and Upper Ordovician Upper Ordovician Upper Ordovician 

Formation top (relative to KB) (ft) -4,479 -5,054 -7,330 

Formation top (relative to GL) (ft) -4,465 -5,041 -7,315 

Formation top (relative to SL) (ft) -3,477 -4,442 -5,555 
Appendix 1. 53

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number

American Petroleum Institute 

well number

Lease name

Permanent datum

Ground level elevation (ft)

Kelly bushing elevation (ft)

Measured from

Drill depth (ft)

6

31–101–03924

No. 1 Robert Olin

GL

1,645

1,658

KB

13,508

7

37–117–20057

No. 1 Harry P. Dewey

GL

1,569

1,587

KB

15,082

8

37–105–20182

No. 1 Pa. Dept. of Forest and 

Water Tract 129

GL

1,847

1,870

KB

18,834

9

37–035–20276

No. 1 Pa. State Forest, 

Tract 285–1

GL

2,004

2,037

KB

19,360

10

37–081–90002

No. 1 W.E. Snyder

DF

726

726

KB

5,808

Formation 37 Black River Group (argillaceous 

limestone and dolomite)

Rose Hill Formation (lower 

limestone member)

Bloomsburg Formation (red 

shale)

Mifflintown Formation 

(McKenzie Member)

System or series: Middle and Upper Ordovician lower Silurian upper Silurian Silurian

Formation top (relative to KB) (ft) -10,707 -8,520 -8,956 -10,212

Formation top (relative to GL) (ft) -10,694 -8,502 -8,933 -10,179

Formation top (relative to SL) (ft) -9,049 -6,933 -7,086 -8,175

Formation 38 Beekmantown Group (Bellefonte 

Formation) (upper part)

Tuscarora Formation (Castanea 

Member) (sandstone)

Mifflintown Formation 

(McKenzie Member)

Mifflintown Formation 

(Rochester Member)

System or series: Middle Ordovician Silurian Silurian Silurian

Formation top (relative to KB) (ft) -10,850 -8,530 -9,068 -10,408

Formation top (relative to GL) (ft) -10,837 -8,512 -9,045 -10,375

Formation top (relative to SL) (ft) -9,192 -6,943 -7,198 -8,371

Formation 39 Tribes Hill Dolomite (Knox 

unconformity)

Tuscarora Formation (main 

body) (sandstone)

Mifflintown Formation 

(Rochester Member)

Keefer Formation

System or series: Lower Ordovician Silurian Silurian Upper Devonian

Formation top (relative to KB) (ft) -10,970 -8,668 -9,388 -10,481

Formation top (relative to GL) (ft) -10,957 -8,650 -9,365 -10,448

Formation top (relative to SL) (ft) -9,312 -7,081 -7,518 -8,444

Formation 40 Little Falls Dolomite Juniata Formation (red shale) 

(Cherokee unconformity)

Keefer Formation (equiv. to 

Irondequoit Ls. of N.Y.)

Rose Hill Formation (upper shale 

member)

System or series: Upper Cambrian Upper Ordovician Upper Devonian lower Silurian

Formation top (relative to KB) (ft) -11,360 -8,816 -9,458 -10,528

Formation top (relative to GL) (ft) -11,347 -8,798 -9,435 -10,495

Formation top (relative to SL) (ft) -9,702 -7,229 -7,588 -8,491
54 Geologic Cross Section A–A′ Through the Appalachian Basin

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number 1 2 3 4 5 

American Petroleum Institute 

well number 31–037–05117 31–037–04593 31–051–04552 31–051–04630 31–101–21496 

Lease name No. 1 J. Klotzbach No. 1 L. Tyler No. 1 Albert McClurg No. 1 Arthur N. Kennedy No. 1 Hubbard 

Permanent datum GL GL GL GL GL 

Ground level elevation (ft) 862 703 988.5 599 1,760 

Kelly bushing elevation (ft) 870 716 1,003 612 1,775 

Measured from KB KB KB KB KB 

Drill depth (ft) 3,950 4,000 5,648 6,387 10,061 

Formation 41 Black River Group (marker x) Black River Group (unnamed 

bentonite bed)

Trenton Group (Millbrig 

Bentonite Bed)

System or series: Middle and Upper Ordovician Middle and Upper Ordovician Upper Ordovician 

Formation top (relative to KB) (ft) -4,660 -5,082 -7,942 

Formation top (relative to GL) (ft) -4,646 -5,069 -7,927 

Formation top (relative to SL) (ft) -3,658 -4,470 -6,167 

Formation 42 Black River Group (marker y) Black River Group (marker x) Trenton Group (Deicke 

Bentonite Bed)

System or series: Middle and Upper Ordovician Middle and Upper Ordovician Upper Ordovician 

Formation top (relative to KB) (ft) -4,723 -5,278 -7,968 

Formation top (relative to GL) (ft) -4,709 -5,265 -7,953 

Formation top (relative to SL) (ft) -3,721 -4,666 -6,193 

Formation 43 Black River Group (argillaceous 

limestone and dolomite)

Black River Group (marker y) Black River Group (unnamed 

bentonite bed)

System or series: Middle and Upper Ordovician Middle and Upper Ordovician Middle and Upper Ordovician 

Formation top (relative to KB) (ft) -4,778 -5,358 -7,983 

Formation top (relative to GL) (ft) -4,764 -5,345 -7,968 

Formation top (relative to SL) (ft) -3,776 -4,746 -6,208 
Appendix 1. 55

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number

American Petroleum Institute 

well number

Lease name

Permanent datum

Ground level elevation (ft)

Kelly bushing elevation (ft)

Measured from

Drill depth (ft)

6

31–101–03924

No. 1 Robert Olin

GL

1,645

1,658

KB

13,508

7

37–117–20057

No. 1 Harry P. Dewey

GL

1,569

1,587

KB

15,082

8

37–105–20182

No. 1 Pa. Dept. of Forest and 

Water Tract 129

GL

1,847

1,870

KB

18,834

9

37–035–20276

No. 1 Pa. State Forest, 

Tract 285–1

GL

2,004

2,037

KB

19,360

10

37–081–90002

No. 1 W.E. Snyder

DF

726

726

KB

5,808

Formation 41 Galway Formation (A sandstone) Bald Eagle Formation 

(sandstone)

Rose Hill Formation (upper shale 

member)

Rose Hill Formation (upper 

limestone member)

System or series: Upper Cambrian Upper Ordovician lower Silurian lower Silurian

Formation top (relative to KB) (ft) -11,750 -9,478 -9,516 -10,853

Formation top (relative to GL) (ft) -11,737 -9,460 -9,493 -10,820

Formation top (relative to SL) (ft) -10,092 -7,891 -7,646 -8,816

Formation 42 Galway Formation

(A interbedded sandstone and 

dolomite, and A dolomite) 

(undivided)

Reedsville Shale Rose Hill Formation (upper 

limestone member)

Rose Hill Formation (lower shale 

member)

System or series: Upper Cambrian Upper Ordovician lower Silurian lower Silurian

Formation top (relative to KB) (ft) -12,044 -10,664 -9,800 -10,890

Formation top (relative to GL) (ft) -12,031 -10,646 -9,777 -10,857

Formation top (relative to SL) (ft) -10,386 -9,077 -7,930 -8,853

Formation 43 Galway Formation

(B sandstone)

Utica (Antes) Shale Rose Hill Formation (lower shale 

member)

Rose Hill Formation (lower 

limestone member)

System or series: Upper Cambrian Upper Ordovician lower Silurian lower Silurian

Formation top (relative to KB) (ft) -12,410 -11,262 -9,818 -10,988

Formation top (relative to GL) (ft) -12,397 -11,244 -9,795 -10,955

Formation top (relative to SL) (ft) -10,752 -9,675 -7,948 -8,951
56 Geologic Cross Section A–A′ Through the Appalachian Basin

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number 1 2 3 4 5 

American Petroleum Institute 

well number 31–037–05117 31–037–04593 31–051–04552 31–051–04630 31–101–21496 

Lease name No. 1 J. Klotzbach No. 1 L. Tyler No. 1 Albert McClurg No. 1 Arthur N. Kennedy No. 1 Hubbard 

Permanent datum GL GL GL GL GL 

Ground level elevation (ft) 862 703 988.5 599 1,760 

Kelly bushing elevation (ft) 870 716 1,003 612 1,775 

Measured from KB KB KB KB KB 

Drill depth (ft) 3,950 4,000 5,648 6,387 10,061 

Formation 44 Galway Formation (sandstone) 

(Knox unconformity)

Black River Group (argillaceous 

limestone and dolomite)

Black River Group (marker x) 

System or series: Upper Cambrian Middle and Upper Ordovician Middle and Upper Ordovician 

Formation top (relative to KB) (ft) -4,880 -5,420 -8,268 

Formation top (relative to GL) (ft) -4,866 -5,407 -8,253 

Formation top (relative to SL) (ft) -3,878 -4,808 -6,493 

Formation 45 Galway Formation (dolomite) Little Falls Dolomite (Knox 

unconformity)

Black River Group (marker y) 

System or series: Upper Cambrian Upper Cambrian Middle and Upper Ordovician 

Formation top (relative to KB) (ft) -4,950 -5,530 -8,332 

Formation top (relative to GL) (ft) -4,936 -5,517 -8,317 

Formation top (relative to SL) (ft) -3,948 -4,918 -6,557 

Formation 46 Galway Formation (sandstone) Galway Formation (upper 

sandstone member)

Black River Group (argillaceous 

limestone and dolomite)

System or series: Upper Cambrian Upper Cambrian Middle and Upper Ordovician 

Formation top (relative to KB) (ft) -5,192 -5,620 -8,402 

Formation top (relative to GL) (ft) -5,178 -5,607 -8,387 

Formation top (relative to SL) (ft) -4,190 -5,008 -6,627 
Appendix 1. 57

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number

American Petroleum Institute 

well number

Lease name

Permanent datum

Ground level elevation (ft)

Kelly bushing elevation (ft)

Measured from

Drill depth (ft)

6

31–101–03924

No. 1 Robert Olin

GL

1,645

1,658

KB

13,508

7

37–117–20057

No. 1 Harry P. Dewey

GL

1,569

1,587

KB

15,082

8

37–105–20182

No. 1 Pa. Dept. of Forest and 

Water Tract 129

GL

1,847

1,870

KB

18,834

9

37–035–20276

No. 1 Pa. State Forest, 

Tract 285–1

GL

2,004

2,037

KB

19,360

10

37–081–90002

No. 1 W.E. Snyder

DF

726

726

KB

5,808

Formation 44 Galway Formation

(B dolomite)

Trenton Group (limestone) Rose Hill Formation (lower 

limestone member)

Tuscarora Formation (Castanea 

Member) (sandstone)

System or series: Upper Cambrian Upper Ordovician lower Silurian Silurian

Formation top (relative to KB) (ft) -12,600 -11,494 -9,905 -10,995

Formation top (relative to GL) (ft) -12,587 -11,476 -9,882 -10,962

Formation top (relative to SL) (ft) -10,942 -9,907 -8,035 -8,958

Formation 45 Galway Formation

(B interbedded sandstone and 

dolomite)

Trenton Group (Millbrig 

Bentonite Bed)

Tuscarora Formation (Castanea 

Member) (sandstone)

Tuscarora Formation (main 

body)

System or series: Upper Cambrian Upper Ordovician Silurian Silurian

Formation top (relative to KB) (ft) -12,750 -12,360 -9,914 -11,087

Formation top (relative to GL) (ft) -12,737 -12,342 -9,891 -11,054

Formation top (relative to SL) (ft) -11,092 -10,773 -8,044 -9,050

Formation 46 Galway Formation

(C sandstone)

Trenton Group (Deicke 

Bentonite Bed)

Tuscarora Formation (main 

body) (sandstone)

Juniata Formation (red shale) 

(Cherokee unconformity)

System or series: Upper Cambrian Upper Ordovician Silurian Upper Ordovician

Formation top (relative to KB) (ft) -12,900 -12,380 -9,985 -11,407

Formation top (relative to GL) (ft) -12,887 -12,362 -9,962 -11,374

Formation top (relative to SL) (ft) -11,242 -10,793 -8,115 -9,370
58 Geologic Cross Section A–A′ Through the Appalachian Basin

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number 1 2 3 4 5 

American Petroleum Institute 

well number 31–037–05117 31–037–04593 31–051–04552 31–051–04630 31–101–21496 

Lease name No. 1 J. Klotzbach No. 1 L. Tyler No. 1 Albert McClurg No. 1 Arthur N. Kennedy No. 1 Hubbard 

Permanent datum GL GL GL GL GL 

Ground level elevation (ft) 862 703 988.5 599 1,760 

Kelly bushing elevation (ft) 870 716 1,003 612 1,775 

Measured from KB KB KB KB KB 

Drill depth (ft) 3,950 4,000 5,648 6,387 10,061 

Formation 47 Galway Formation (sandy 

dolomite)

Galway Formation (dolomite) Little Falls Dolomite (Knox 

unconformity)

System or series: Upper Cambrian Upper Cambrian Upper Cambrian 

Formation top (relative to KB) (ft) -5,253 -5,770 -8,530 

Formation top (relative to GL) (ft) -5,239 -5,757 -8,515 

Formation top (relative to SL) (ft) -4,251 -5,158 -6,755 

Formation 48 Potsdam Sandstone (or 

lowermost Galway)

Potsdam Sandstone Galway Formation (upper 

sandstone member)

System or series: Upper Cambrian Middle Cambrian Upper Cambrian 

Formation top (relative to KB) (ft) -5,440 -6,387 -8,928 

Formation top (relative to GL) (ft) -5,426 -6,374 -8,913 

Formation top (relative to SL) (ft) -4,438 -5,775 -7,153 

Formation 49 granite and (or) gneiss Galway Formation (dolomite) 

System or series: Mesoproterozoic Upper Cambrian 

Formation top (relative to KB) (ft) -5,557 -9,168 

Formation top (relative to GL) (ft) -5,543 -9,153 

Formation top (relative to SL) (ft) -4,555 -7,393 

Formation 50 Potsdam Sandstone 

System or series: Middle Cambrian 

Formation top (relative to KB) (ft) -9,843 

Formation top (relative to GL) (ft) -9,828 

Formation top (relative to SL) (ft) -8,068 
Appendix 1. 59

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number

American Petroleum Institute 

well number

Lease name

Permanent datum

Ground level elevation (ft)

Kelly bushing elevation (ft)

Measured from

Drill depth (ft)

6

31–101–03924

No. 1 Robert Olin

GL

1,645

1,658

KB

13,508

7

37–117–20057

No. 1 Harry P. Dewey

GL

1,569

1,587

KB

15,082

8

37–105–20182

No. 1 Pa. Dept. of Forest and 

Water Tract 129

GL

1,847

1,870

KB

18,834

9

37–035–20276

No. 1 Pa. State Forest, 

Tract 285–1

GL

2,004

2,037

KB

19,360

10

37–081–90002

No. 1 W.E. Snyder

DF

726

726

KB

5,808

Formation 47 Potsdam Sandstone Trenton Group (unnamed 

bentonite bed)

Juniata Formation (red shale) 

(Cherokee unconformity)

Bald Eagle Formation 

(sandstone)

System or series: Middle Cambrian Upper Ordovician Upper Ordovician Upper Ordovician

Formation top (relative to KB) (ft) -13,100 -12,400 -10,297 -12,243

Formation top (relative to GL) (ft) -13,087 -12,382 -10,274 -12,210

Formation top (relative to SL) (ft) -11,442 -10,813 -8,427 -10,206

Formation 48 Black River Group (limestone) Bald Eagle Formation 

(sandstone)

Reedsville Shale

System or series: Middle and Upper Ordovician Upper Ordovician Upper Ordovician

Formation top (relative to KB) (ft) -12,403 -11,200 -13,453

Formation top (relative to GL) (ft) -12,385 -11,177 -13,420

Formation top (relative to SL) (ft) -10,816 -9,330 -11,416

Formation 49 Black River Group (marker x) Reedsville Shale Utica (Antes) Shale

System or series: Middle and Upper Ordovician Upper Ordovician Upper Ordovician

Formation top (relative to KB) (ft) -12,914 -12,350 -14,060

Formation top (relative to GL) (ft) -12,896 -12,327 -14,027

Formation top (relative to SL) (ft) -11,327 -10,480 -12,023

Formation 50 Black River Group (marker y) Utica (Antes) Shale Trenton Group (limestone)

System or series: Middle and Upper Ordovician Upper Ordovician Upper Ordovician

Formation top (relative to KB) (ft) -13,024 -12,930 -14,390

Formation top (relative to GL) (ft) -13,006 -12,907 -14,357

Formation top (relative to SL) (ft) -11,437 -11,060 -12,353
60 Geologic Cross Section A–A′ Through the Appalachian Basin

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number 1 2 3 4 5 

American Petroleum Institute 

well number 31–037–05117 31–037–04593 31–051–04552 31–051–04630 31–101–21496 

Lease name No. 1 J. Klotzbach No. 1 L. Tyler No. 1 Albert McClurg No. 1 Arthur N. Kennedy No. 1 Hubbard 

Permanent datum GL GL GL GL GL 

Ground level elevation (ft) 862 703 988.5 599 1,760 

Kelly bushing elevation (ft) 870 716 1,003 612 1,775 

Measured from KB KB KB KB KB 

Drill depth (ft) 3,950 4,000 5,648 6,387 10,061 

Formation 51 

System or series: 

Formation top (relative to KB) (ft) 

Formation top (relative to GL) (ft) 

Formation top (relative to SL) (ft) 

Formation 52 

System or series: 

Formation top (relative to KB) (ft) 

Formation top (relative to GL) (ft) 

Formation top (relative to SL) (ft) 

Formation 53 

System or series: 

Formation top (relative to KB) (ft) 

Formation top (relative to GL) (ft) 

Formation top (relative to SL) (ft) 
Appendix 1. 61

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number

American Petroleum Institute 

well number

Lease name

Permanent datum

Ground level elevation (ft)

Kelly bushing elevation (ft)

Measured from

Drill depth (ft)

6

31–101–03924

No. 1 Robert Olin

GL

1,645

1,658

KB

13,508

7

37–117–20057

No. 1 Harry P. Dewey

GL

1,569

1,587

KB

15,082

8

37–105–20182

No. 1 Pa. Dept. of Forest and 

Water Tract 129

GL

1,847

1,870

KB

18,834

9

37–035–20276

No. 1 Pa. State Forest, 

Tract 285–1

GL

2,004

2,037

KB

19,360

10

37–081–90002

No. 1 W.E. Snyder

DF

726

726

KB

5,808

Formation 51 Loysburg Formation 

(argillaceous limestone and 

dolomite)

Trenton Group (limestone) Trenton Group (Millbrig 

Bentonite Bed)

System or series: Middle and Upper Ordovician Upper Ordovician Upper Ordovician

Formation top (relative to KB) (ft) -13,095 -13,180 -14,703

Formation top (relative to GL) (ft) -13,077 -13,157 -14,670

Formation top (relative to SL) (ft) -11,508 -11,310 -12,666

Formation 52 Beekmantown Group (Bellefonte 

Formation) (upper part)

Trenton Group (Millbrig 

Bentonite Bed)

Trenton Group (Deicke 

Bentonite Bed)

System or series: Middle Ordovician Upper Ordovician Upper Ordovician

Formation top (relative to KB) (ft) -13,194 -13,870 -14,728

Formation top (relative to GL) (ft) -13,176 -13,847 -14,695

Formation top (relative to SL) (ft) -11,607 -12,000 -12,691

Formation 53 Beekmantown Group (Bellefonte 

Formation) (lower part) 

(unconformity)

Trenton Group (Deicke 

Bentonite Bed)

Trenton Group (unnamed 

bentonite bed)

System or series: Middle Ordovician Upper Ordovician Upper Ordovician

Formation top (relative to KB) (ft) -13,700 -13,888 -14,756

Formation top (relative to GL) (ft) -13,682 -13,865 -14,723

Formation top (relative to SL) (ft) -12,113 -12,018 -12,719
62 Geologic Cross Section A–A′ Through the Appalachian Basin

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number 1 2 3 4 5 

American Petroleum Institute 

well number 31–037–05117 31–037–04593 31–051–04552 31–051–04630 31–101–21496 

Lease name No. 1 J. Klotzbach No. 1 L. Tyler No. 1 Albert McClurg No. 1 Arthur N. Kennedy No. 1 Hubbard 

Permanent datum GL GL GL GL GL 

Ground level elevation (ft) 862 703 988.5 599 1,760 

Kelly bushing elevation (ft) 870 716 1,003 612 1,775 

Measured from KB KB KB KB KB 

Drill depth (ft) 3,950 4,000 5,648 6,387 10,061 

Formation 54 

System or series: 

Formation top (relative to KB) (ft) 

Formation top (relative to GL) (ft) 

Formation top (relative to SL) (ft) 

Formation 55 

System or series: 

Formation top (relative to KB) (ft) 

Formation top (relative to GL) (ft) 

Formation top (relative to SL) (ft) 

Formation 56 

System or series: 

Formation top (relative to KB) (ft) 

Formation top (relative to GL) (ft) 

Formation top (relative to SL) (ft) 
Appendix 1. 63

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number

American Petroleum Institute 

well number

Lease name

Permanent datum

Ground level elevation (ft)

Kelly bushing elevation (ft)

Measured from

Drill depth (ft)

6

31–101–03924

No. 1 Robert Olin

GL

1,645

1,658

KB

13,508

7

37–117–20057

No. 1 Harry P. Dewey

GL

1,569

1,587

KB

15,082

8

37–105–20182

No. 1 Pa. Dept. of Forest and 

Water Tract 129

GL

1,847

1,870

KB

18,834

9

37–035–20276

No. 1 Pa. State Forest, 

Tract 285–1

GL

2,004

2,037

KB

19,360

10

37–081–90002

No. 1 W.E. Snyder

DF

726

726

KB

5,808

Formation 54 Beekmantown Group (Larke 

Formation) (Knox unconformity)

Trenton Group (unnamed 

bentonite bed)

Black River Group (limestone)

System or series: Lower Ordovician Upper Ordovician Middle and Upper Ordovician

Formation top (relative to KB) (ft) -13,992 -13,908 -14,910

Formation top (relative to GL) (ft) -13,974 -13,885 -14,877

Formation top (relative to SL) (ft) -12,405 -12,038 -12,873

Formation 55 Gatesburg Formation (Mines 

Dolomite Member)

Black River Group (limestone) Black River Group (marker x)

System or series: Upper Cambrian Middle and Upper Ordovician Middle and Upper Ordovician

Formation top (relative to KB) (ft) -14,445 -13,986 -15,030

Formation top (relative to GL) (ft) -14,427 -13,963 -14,997

Formation top (relative to SL) (ft) -12,858 -12,116 -12,993

Formation 56 Gatesburg Formation (upper 

sandy member)

Black River Group (marker x) Black River Group (marker y)

System or series: Upper Cambrian Middle and Upper Ordovician Middle and Upper Ordovician

Formation top (relative to KB) (ft) -14,840 -14,310 -15,158

Formation top (relative to GL) (ft) -14,822 -14,287 -15,125

Formation top (relative to SL) (ft) -13,253 -12,440 -13,121
64 Geologic Cross Section A–A′ Through the Appalachian Basin

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number 1 2 3 4 5 

American Petroleum Institute 

well number 31–037–05117 31–037–04593 31–051–04552 31–051–04630 31–101–21496 

Lease name No. 1 J. Klotzbach No. 1 L. Tyler No. 1 Albert McClurg No. 1 Arthur N. Kennedy No. 1 Hubbard 

Permanent datum GL GL GL GL GL 

Ground level elevation (ft) 862 703 988.5 599 1,760 

Kelly bushing elevation (ft) 870 716 1,003 612 1,775 

Measured from KB KB KB KB KB 

Drill depth (ft) 3,950 4,000 5,648 6,387 10,061 

Formation 57 

System or series: 

Formation top (relative to KB) (ft) 

Formation top (relative to GL) (ft) 

Formation top (relative to SL) (ft) 

Formation 58 

System or series: 

Formation top (relative to KB) (ft) 

Formation top (relative to GL) (ft) 

Formation top (relative to SL) (ft) 

Formation 59 

System or series: 

Formation top (relative to KB) (ft) 

Formation top (relative to GL) (ft) 

Formation top (relative to SL) (ft) 
Appendix 1. 65

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number

American Petroleum Institute 

well number

Lease name

Permanent datum

Ground level elevation (ft)

Kelly bushing elevation (ft)

Measured from

Drill depth (ft)

6

31–101–03924

No. 1 Robert Olin

GL

1,645

1,658

KB

13,508

7

37–117–20057

No. 1 Harry P. Dewey

GL

1,569

1,587

KB

15,082

8

37–105–20182

No. 1 Pa. Dept. of Forest and 

Water Tract 129

GL

1,847

1,870

KB

18,834

9

37–035–20276

No. 1 Pa. State Forest, 

Tract 285–1

GL

2,004

2,037

KB

19,360

10

37–081–90002

No. 1 W.E. Snyder

DF

726

726

KB

5,808

Formation 57 Black River Group (marker y) Loysburg Formation 

(argillaceous limestone and 

dolomite)

System or series: Middle and Upper Ordovician Middle and Upper Ordovician

Formation top (relative to KB) (ft) -14,436 -15,228

Formation top (relative to GL) (ft) -14,413 -15,195

Formation top (relative to SL) (ft) -12,566 -13,191

Formation 58 Loysburg Formation 

(argillaceous limestone and 

dolomite)

Beekmantown Group (Bellefonte 

Formation) (upper part)

System or series: Middle and Upper Ordovician Middle Ordovician

Formation top (relative to KB) (ft) -14,503 -15,417

Formation top (relative to GL) (ft) -14,480 -15,384

Formation top (relative to SL) (ft) -12,633 -13,380

Formation 59 Beekmantown Group (Bellefonte 

Formation) (upper part)

Beekmantown Group (Bellefonte 

Formation) (lower part) 

(unconformity)

System or series: Middle Ordovician Middle Ordovician

Formation top (relative to KB) (ft) -14,710 -15,599

Formation top (relative to GL) (ft) -14,687 -15,566

Formation top (relative to SL) (ft) -12,840 -13,562
66 Geologic Cross Section A–A′ Through the Appalachian Basin

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number 1 2 3 4 5 

American Petroleum Institute 

well number 31–037–05117 31–037–04593 31–051–04552 31–051–04630 31–101–21496 

Lease name No. 1 J. Klotzbach No. 1 L. Tyler No. 1 Albert McClurg No. 1 Arthur N. Kennedy No. 1 Hubbard 

Permanent datum GL GL GL GL GL 

Ground level elevation (ft) 862 703 988.5 599 1,760 

Kelly bushing elevation (ft) 870 716 1,003 612 1,775 

Measured from KB KB KB KB KB 

Drill depth (ft) 3,950 4,000 5,648 6,387 10,061 

Formation 60 

System or series: 

Formation top (relative to KB) (ft) 

Formation top (relative to GL) (ft) 

Formation top (relative to SL) (ft) 

Formation 61 

System or series: 

Formation top (relative to KB) (ft) 

Formation top (relative to GL) (ft) 

Formation top (relative to SL) (ft) 

Formation 62 

System or series: 

Formation top (relative to KB) (ft) 

Formation top (relative to GL) (ft) 

Formation top (relative to SL) (ft) 
Appendix 1. 67

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number

American Petroleum Institute 

well number

Lease name

Permanent datum

Ground level elevation (ft)

Kelly bushing elevation (ft)

Measured from

Drill depth (ft)

6

31–101–03924

No. 1 Robert Olin

GL

1,645

1,658

KB

13,508

7

37–117–20057

No. 1 Harry P. Dewey

GL

1,569

1,587

KB

15,082

8

37–105–20182

No. 1 Pa. Dept. of Forest and 

Water Tract 129

GL

1,847

1,870

KB

18,834

9

37–035–20276

No. 1 Pa. State Forest, 

Tract 285–1

GL

2,004

2,037

KB

19,360

10

37–081–90002

No. 1 W.E. Snyder

DF

726

726

KB

5,808

Formation 60 Beekmantown Group (Bellefonte 

Formation) (lower part) 

(unconformity)

Beekmantown Group (Larke 

Formation) (Knox unconformity)

System or series: Middle Ordovician Lower Ordovician

Formation top (relative to KB) (ft) -14,950 -16,625

Formation top (relative to GL) (ft) -14,927 -16,592

Formation top (relative to SL) (ft) -13,080 -14,588

Formation 61 Beekmantown Group (Larke 

Formation) (Knox unconformity)

Gatesburg Formation (Mines 

Dolomite Member)

System or series: Lower Ordovician Upper Cambrian

Formation top (relative to KB) (ft) -15,520 -17,065

Formation top (relative to GL) (ft) -15,497 -17,032

Formation top (relative to SL) (ft) -13,650 -15,028

Formation 62 Gatesburg Formation (Mines 

Dolomite Member)

Gatesburg Formation (upper 

sandy member)

System or series: Upper Cambrian Upper Cambrian

Formation top (relative to KB) (ft) -15,956 -17,400

Formation top (relative to GL) (ft) -15,933 -17,367

Formation top (relative to SL) (ft) -14,086 -15,363
68 Geologic Cross Section A–A′ Through the Appalachian Basin

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number 1 2 3 4 5 

American Petroleum Institute 

well number 31–037–05117 31–037–04593 31–051–04552 31–051–04630 31–101–21496 

Lease name No. 1 J. Klotzbach No. 1 L. Tyler No. 1 Albert McClurg No. 1 Arthur N. Kennedy No. 1 Hubbard 

Permanent datum GL GL GL GL GL 

Ground level elevation (ft) 862 703 988.5 599 1,760 

Kelly bushing elevation (ft) 870 716 1,003 612 1,775 

Measured from KB KB KB KB KB 

Drill depth (ft) 3,950 4,000 5,648 6,387 10,061 

Formation 63 

System or series: 

Formation top (relative to KB) (ft) 

Formation top (relative to GL) (ft) 

Formation top (relative to SL) (ft) 

Formation 64 

System or series: 

Formation top (relative to KB) (ft) 

Formation top (relative to GL) (ft) 

Formation top (relative to SL) (ft) 

Formation 65 

System or series: 

Formation top (relative to KB) (ft) 

Formation top (relative to GL) (ft) 

Formation top (relative to SL) (ft) 

Formation 66 

System or series: 

Formation top (relative to KB) (ft) 

Formation top (relative to GL) (ft) 

Formation top (relative to SL) (ft) 
Appendix 1. 69

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number

American Petroleum Institute 

well number

Lease name

Permanent datum

Ground level elevation (ft)

Kelly bushing elevation (ft)

Measured from

Drill depth (ft)

6

31–101–03924

No. 1 Robert Olin

GL

1,645

1,658

KB

13,508

7

37–117–20057

No. 1 Harry P. Dewey

GL

1,569

1,587

KB

15,082

8

37–105–20182

No. 1 Pa. Dept. of Forest and 

Water Tract 129

GL

1,847

1,870

KB

18,834

9

37–035–20276

No. 1 Pa. State Forest, 

Tract 285–1

GL

2,004

2,037

KB

19,360

10

37–081–90002

No. 1 W.E. Snyder

DF

726

726

KB

5,808

Formation 63 Gatesburg Formation (upper 

sandy member)

Gatesburg Formation (Ore Hill 

Member) (limestone)

System or series: Upper Cambrian Upper Cambrian

Formation top (relative to KB) (ft) -16,384 -17,815

Formation top (relative to GL) (ft) -16,361 -17,782

Formation top (relative to SL) (ft) -14,514 -15,778

Formation 64 Gatesburg Formation (Ore Hill 

Member) (dolomite)

Gatesburg Formation (lower 

sandy member)

System or series: Upper Cambrian Upper Cambrian

Formation top (relative to KB) (ft) -16,790 -18,398

Formation top (relative to GL) (ft) -16,767 -18,365

Formation top (relative to SL) (ft) -14,920 -16,361

Formation 65 Gatesburg Formation (lower 

sandy member)

Warrior Formation (shale and 

dolomite)

System or series: Upper Cambrian Upper Cambrian

Formation top (relative to KB) (ft) -17,590 -18,696

Formation top (relative to GL) (ft) -17,567 -18,663

Formation top (relative to SL) (ft) -15,720 -16,659

Formation 66 Warrior Formation (upper oolitic 

dolomite

Warrior Formation (sandstone)

System or series: Upper Cambrian Middle Cambrian

Formation top (relative to KB) (ft) -17,776 -18,950

Formation top (relative to GL) (ft) -17,753 -18,917

Formation top (relative to SL) (ft) -15,906 -16,913
70 Geologic Cross Section A–A′ Through the Appalachian Basin

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number 1 2 3 4 5 

American Petroleum Institute 

well number 31–037–05117 31–037–04593 31–051–04552 31–051–04630 31–101–21496 

Lease name No. 1 J. Klotzbach No. 1 L. Tyler No. 1 Albert McClurg No. 1 Arthur N. Kennedy No. 1 Hubbard 

Permanent datum GL GL GL GL GL 

Ground level elevation (ft) 862 703 988.5 599 1,760 

Kelly bushing elevation (ft) 870 716 1,003 612 1,775 

Measured from KB KB KB KB KB 

Drill depth (ft) 3,950 4,000 5,648 6,387 10,061 

Formation 67 

System or series: 

Formation top (relative to KB) (ft) 

Formation top (relative to GL) (ft) 

Formation top (relative to SL) (ft) 

Formation 68 

System or series: 

Formation top (relative to KB) (ft) 

Formation top (relative to GL) (ft) 

Formation top (relative to SL) (ft) 

Formation 69 

System or series: 

Formation top (relative to KB) (ft) 

Formation top (relative to GL) (ft) 

Formation top (relative to SL) (ft) 

Formation 70 

System or series: 

Formation top (relative to KB) (ft) 

Formation top (relative to GL) (ft) 

Formation top (relative to SL) (ft) 

1

West River Shale, Genundewa Limestone, Penn Yan Shale, and Lodi Limestone Members of the Genesee Formation are shown as undivided on cross section A–A′ and correlation chart (fig. 3). 

On cross section A–A′, they may also be shown as West River Shale and Genundewa Limestone Members, undivided; and Penn Yan Shale and Lodi Limestone Members, undivided. 2

Not shown on cross section A–A′ or correlation chart (fig. 3) because unit is to thin.
Appendix 1. 71

Appendix 1. Table summarizing stratigraphic units and depths of stratigraphic units for drill holes 1–10 in cross section A–A′.—Continued

[Abbreviations: Dept., Department; DF, drill floor; equiv., equivalent; Fm., Formation; ft, feet; GL, ground level; KB, kelly bushing; Ls., Limestone; No., number; N.Y., New York; Pa., Pennsylvania; 

Sh., Shale; SL, sea level]

Drill-hole number

American Petroleum Institute 

well number

Lease name

Permanent datum

Ground level elevation (ft)

Kelly bushing elevation (ft)

Measured from

Drill depth (ft)

6

31–101–03924

No. 1 Robert Olin

GL

1,645

1,658

KB

13,508

7

37–117–20057

No. 1 Harry P. Dewey

GL

1,569

1,587

KB

15,082

8

37–105–20182

No. 1 Pa. Dept. of Forest and 

Water Tract 129

GL

1,847

1,870

KB

18,834

9

37–035–20276

No. 1 Pa. State Forest, 

Tract 285–1

GL

2,004

2,037

KB

19,360

10

37–081–90002

No. 1 W.E. Snyder

DF

726

726

KB

5,808

Formation 67 Warrior Formation (shale and 

dolomite)

Warrior Formation (sandy 

dolomite)

System or series: Upper Cambrian Middle Cambrian

Formation top (relative to KB) (ft) -17,850 -19,267

Formation top (relative to GL) (ft) -17,827 -19,234

Formation top (relative to SL) (ft) -15,980 -17,230

Formation 68 Warrior Formation (sandstone)

System or series: Middle Cambrian

Formation top (relative to KB) (ft) -18,100

Formation top (relative to GL) (ft) -18,077

Formation top (relative to SL) (ft) -16,230

Formation 69 Warrior Formation (sandy 

dolomite)

System or series: Middle Cambrian

Formation top (relative to KB) (ft) -18,590

Formation top (relative to GL) (ft) -18,567

Formation top (relative to SL) (ft) -16,720

Formation 70 Potsdam Sandstone

System or series: Middle Cambrian

Formation top (relative to KB) (ft) -18,700

Formation top (relative to GL) (ft) -18,677

Formation top (relative to SL) (ft) -16,830

Appendix 2. Scale, Units, and Depths for Gamma-Ray Logging Runs
74 Geologic Cross Section A–A′ Through the Appalachian Basin

Appendix 2. Scale, units, and depths for gamma-ray logging runs.

[Abbreviations: API, American Petroleum Institute; ft, feet; KB, kelly bushing; na, not applicable; nd, no data; TD, total depth; μgm Ra-eq/ton, micrograms of radium equivalent per 

metric ton; μR/hr, micro-Roentgens per hour]

Drill-hole

number Scale and units Depth of selected logged intervals Notes

1 0–200 API units 83 ft below KB to 3,899 ft TD is 3,950 ft below KB

2 0–200 API units

200–400 API units (backup scale)

KB to TD TD is 4,000 ft below KB

3 0–200 API units

200–400 API units (backup scale)

400–600 API units (second backup scale)

600–800 API units (third backup scale)

KB to TD TD is 5,648 ft below KB

4 0–200 API units

200–400 API units (backup scale)

400–600 API units (second backup scale)

29.5 ft below KB to TD TD is 6,388 ft below KB

5 0–200 API units

200–400 API units (backup scale)

400–600 API units (second backup scale)

KB to TD TD is 10,051 ft below KB

6 0–13.5 μR/hr

13.5–26 μR/hr (backup scale)

4,000.5 ft below KB to 6,292.5 ft Birdwell log

0–7.5 μgm Ra-eq/ton

7.5–15 μgm Ra-eq/ton (backup scale)

6,292.5 ft below KB to 12,646.5 ft Schlumberger log

0–10.5 μgm Ra-eq/ton

10.5–21 μgm Ra-eq/ton (backup scale)

12,646.5 ft below KB to TD Schlumberger log; TD is 13,508 ft below KB

7 0–200 API units

200–400 API units (backup scale)

100 ft below KB to 13,400.5 ft na

0–200 API units

200–400 API units (backup scale)

13,400.5 ft below KB to 14,982 ft TD is 15,082 ft below KB

8 0–110 API units KB to 6,486 ft Birdwell log (curve extends beyond scale maximum)

0–150 API units

150–300 API units (backup scale)

6,486 ft below KB to 18,796.5 ft Schlumberger log; TD is 18,834 ft below KB

9 0–200 API units

200–400 API units (backup scale)

200 ft below KB to 19,357 ft TD is 19,365 ft below KB

10 nd nd na

Trippi and others—Geologic Cross Section A–A′ Through the Appalachian Basin—SIM 3425

ISSN 2329-1311 (print)

ISSN 2329-132X (online)

https://doi.org/10.3133/sim3425 Printed on recycled paper