DEVONIAN MISSISSIPPIAN were deepened by scour and were then partly refilled with outwash material when the ice melted. STRATIGRAPHY The outcropping sedimentary rocks, excluding the deposits of Quaternary age, are about 4,000 feet thick and range in age from Late Devonian to Middle Pennsylvanian. They include the upper part of the Catskill Formation, the Pocono and Pottsville Formations, and part of the post-Pottsville rocks (pls. 1 and 3). The Transcontinental Production Co. Richards 1 well, drilled about 1 mile north of the town of Ransom, penetrated about 8,618 feet of strata. In this report those strata tentatively assigned to or correlated with 11 Devonian formations (fig. 2, pl. 2) extend downward from the Catskill For Susquehanna 2 Formation divided into several members in area of outcrop. Pennsylvanian rocks in the Ransom quadrangle, Pennsylvania. mation of the Susquehanna Group to the Kalkberg Limestone of the Helderberg Group. This well has apparently penetrated all but the lowermost few feet of rocks of the Devonian System that underlie the quadrangle. DEVONIAN SYSTEM LOWER DEVONIAN SERIES HELDERBERG GROUP The name Helderberg was used by Vanuxem (1842, p. 111) for the strata prominently exposed in the Helderberg Mountains of New York. Some years later Hall (1851, p. 162) divided the formation into the Upper Helderberg and the Lower Helderberg. The Helderberg Group of present usage is largely equivalent to Hall's Lower Helderberg, except that the Manlius Limestone of Clarke and Schuchert (1899) and of later geologists is no longer included. In much of northeastern Pennsylvania the Helderberg is divided, in ascending stratigraphic order, into the Coeymans Limestone, Kalkberg Limestone, New Scotland Limestone equivalent, Becraft Limestone, and Port Ewen Limestone equivalent. The lower 300 feet of rock in the Richards 1 well is assigned to these formations (pl. 2), with the exception of the Coeymans Limestone, which (if present) presumably lies below the bottom of the hole. Jones and Cate (1957, pl. 1) reported that the Helderberg Group is more than 200 feet thick in this part of the State. Furthermore, their data show that the Helderberg should consist mostly of shale in this area; data from the Richards 1 well show this too. KALKBERG LIMESTONE Name and age. The name Kalkberg Limestone was proposed by Chadwick (1908, p. 348) for the limestone strata containing chert nodules that lie below the New Scotland Limestone in Greene County, N.Y. The impure siliceous limestone containing dark chert nodules and lying at the base of the New Scotland Limestone in Pennsylvania was considered by Swartz (1939, p. 55, 56) to be correlative with the Kalkberg Limestone of New York. The lower 35 feet of strata penetrated by the Richards 1 well is here provisionally assigned to the Kalkberg Limestone of Early Devonian age. from Distribution and thickness.-The Kalkberg Limestone crops out in eastern Pennsylvania, where its thickness is reported to range 25 to 30 feet (Swartz, 1939, p. 58). Thus the lower 35 feet of strata in the Richards 1 well probably represents nearly the full thickness of the formation. The lower part of this sequence may also represent the upper part of the Coeymans Limestone, but only if the Stormville Conglomerate of I. C. White (1882, p. 132) is missing from the top of the Coeymans in this area. Lithology. The Kalkberg, as determined from the cuttings from the Richards 1 well, consists of medium-gray to medium-light-gray very silty fine-grained limestone. It contains about 5 percent mediumgray to light-brownish-gray dense chert and a trace of pyrite. The limestone contains a few brachiopods and ostracodes. NEW SCOTLAND LIMESTONE EQUIVALENT Name and age.-The name New Scotland Limestone was proposed by Clarke and Schuchert (1899, p. 877) for rock exposures near New Scotland, Albany County, N.Y., where these rocks overlie the Kalkberg Limestone and underlie the Becraft Limestone. In this report the unit is referred to as the New Scotland Limestone equivalent, because in the Ransom quadrangle the lithology of this unit is mainly limy shale. Swartz (1939, p. 55-62) considered the New Scotland to be of Early Devonian age and correlated it with the New Scotland Limestone or equivalent strata in adjacent States. Distribution and thickness.—The New Scotland Limestone is probably present throughout most of the Valley and Ridge province of Pennsylvania, but it has not been observed in the western part of Schuylkill County (Swartz, 1939, p. 55). Swartz (1939, p. 58) reported that the New Scotland Limestone is about 80 feet thick in the eastern part of Monroe County and that it varies in thickness from 10 to 30 feet in central Pennsylvania. Approximately 66 feet of strata penetrated by the Richards 1 well is tentatively assigned to the New Scotland Limestone equivalent. Lithology. In outcrops in eastern Pennsylvania the New Scotland consists of dark-gray calcareous shale and dark-gray thick-bedded argillaceous limestone that locally contains lenses and nodules of darkgray to black chert that weathers white (Swartz, 1939, p. 55–56). The strata assigned to the New Scotland Limestone equivalent in the Richards 1 well consist of dark-gray finely micaceous very limy shale, part of which is silty, and a few beds of very silty limestone that contain traces of pyrite and a few ostracodes. Stratigraphic relations.-In outcrops the contact of the New Scotland Limestone with the underlying Kalkberg Limestone is apparently transitional (Swartz, 1939, p. 55-60). Well cuttings at this interval also give no evidence of a hiatus. BECRAFT LIMESTONE Name and age.-The name Becraft Limestone was proposed by Darton (1894, p. 212) for the strata exposed near Becraft Mountain, N.Y. The unit had previously been referred to by Vanuxem (1840, p. 377) as the Scutella Limestone. Swartz (1939, p. 62-65) applied the name Becraft Limestone to rocks in northeastern Pennsylvania that are similar in lithology, stratigraphic position, and faunal content to the type Becraft in New York. The Becraft is of Early Devonian age in Pennsylvania. Distribution and thickness.-The Becraft Limestone is about 20 feet thick at the northeast border of Pennsylvania in Monroe County; 10 miles southwest the strata tentatively referred to as the Becraft (Swartz, 1939, p. 62-63) are 14 feet thick and pinch out westward, in the eastern part of Monroe County. On the basis of lithologic similarity and stratigraphic position, 18 feet of the strata penetrated in the Richards 1 well is tentatively assigned to the Becraft Limestone. Lithology. In outcrops the Becraft consists of dark-gray to bluishgray medium- to thick-bedded finely to coarsely crystalline limestone containing some shale or siltstone and dark-gray chert. It is highly fossiliferous in some areas and nearly unfossiliferous in others (Swartz and Swartz, 1941, p. 1162-1174). The Becraft, as determined from the cuttings from the Richards 1 well, consists of medium- to dark-gray finely micaceous pyritic very silty fine-grained limestone containing brachiopods, bryozoans (?), crinoids, and ostracodes. In the lower part of the formation the limestone has interbeds of darkgray very limy shale. Stratigraphic relations.-Where it is present in outcrops, the Becraft Limestone apparently rests conformably on the New Scotland Limestone. Data obtained from the Richards 1 well suggest that the Becraft Limestone and the New Scotland Limestone equivalent are conformable and that the contact may be gradational. PORT EWEN LIMESTONE EQUIVALENT Name and age.-The Port Ewen Limestone of Early Devonian Age was named by Clarke (1903, p. 21) for exposures near Port Ewen, N.Y. Southward, the Port Ewen Limestone loses its calcareous character, and in southeastern New York and northeastern Pennsylvania it is referred to as the Port Ewen Shale (Swartz, 1939, p. 62). The limy shale in the Richards 1 well occupies the same stratigraphic position as the Port Ewen of other areas; hence, in this report the limy shale is referred to as the Port Ewen Limestone equivalent. Distribution and thickness.-Strata equivalent to the Port Ewen Limestone crop out in narrow belts in northeastern Pennsylvania and extend into central and south-central Pennsylvania, where they are represented in part by the Mandata Shale of Swartz (1939, p. 63). The Port Ewen strata are reported to be about 200 feet thick near the New York-New Jersey boundary and are about 150 feet thick near the Pennsylvania-New Jersey boundary (Swartz, 1939, p. 62). In the Ransom quadrangle the Port Ewan Limestone equivalent is about 179 feet thick. Lithology.—At most exposures in northeastern and central Pennsylvania, the Port Ewen Limestone has been described as ash-gray to black siliceous and calcareous shale (Swartz, 1939, p. 62; Swartz and Swartz, 1941, p. 1168-1174). In the Richards 1 well, strata equivalent to the Port Ewen Limestone are medium-gray to grayish-black finely micaceous slightly pyritic very limy shale and siltstone. Stratigraphic relations.—In the northeastern part of the State, the Port Ewen Limestone equivalent can be differentiated easily from the underlying Becraft Limestone (Swartz, 1939, p. 62). In the Richards 1 well the contact of the Port Ewen Limestone equivalent with the Becraft Limestone is arbitrarily placed at the top of the limestone sequence. ORISKANY GROUP The name Oriskany was first applied by Vanuxem (1839, p. 273) to the white sandstone exposed at Oriskany Falls, N.Y. Rogers (1858, p. 107) introduced the name Meridian Sandstone for the strata in Pennsylvania that he correlated with the Oriskany Sandstone of New York. Platt and Platt (1877, p. XXIV) substituted the name Oriskany for the Meridian of Rogers. Cleaves (1939, p. 96-97) raised the Oriskany to group status and divided it into the Shriver Chert and the overlying Ridgeley Sandstone. Rocks of the Oriskany Group crop out in many narrow belts in the Valley and Ridge province. The group may be as much as 350 feet thick in south-central Pennsylvania (Jones and Cate, 1957, pls. 2, 3). The sandstone of the Oriskany Group is reported to be absent from the outcrop and subsurface in a narrow belt that extends from Harrisburg (in the south-central part of the State) to the northeast corner along the "Adirondack-Harrisburg axis" of Woodward (1957, p. 1431-1432). Sandstone is absent in the strata assigned to the Oriskany Group in the Richards 1 well; hence, only the Shriver Chert of the Oriskany Group is inferred to be present in the Ransom quadrangle (pl. 2). Cleaves (1939, p. 97) reported that the Ridgeley Sandstone is of variable lithology and locally grades to a silty limestone; accordingly, the 28-foot-thick upper unit of the Oriskany in the Richards 1 well may be a thin equivalent of the Ridgeley. SHRIVER CHERT Name and age.-The name Shriver Chert Member of the Oriskany Formation was proposed for a unit composed of dark-gray siliceous |