Hamilton Group
Stratigraphic Setting
Stratigraphic Setting
---------------------

In western Pennsylvania, Ohio and West Virginia the Hamilton Group consists of the [Mahantango Formation](/wiki/Mahantango_Formation "Mahantango Formation"), a gray, dark gray, brown, and olive laminated shale; siltstone; and very fine\-grained sandstone or claystone containing marine fossils. The uppermost clay layers of the [Mahantango Formation](/wiki/Mahantango_Formation "Mahantango Formation") are particularly rich in fossils. In New York, central and eastern Pennsylvania the upper sections contain several thick grey shale formations, occasionally marked with limestone stringer. It overlies the [Marcellus Shale](/wiki/Marcellus_Shale "Marcellus Shale"), a [fissile](/wiki/Fissility_%28geology%29 "Fissility (geology)") gray\-black to black, thinly laminated, [pyritic](/wiki/Pyrite "Pyrite"), [carbonaceous](/wiki/Carbon "Carbon") thin shale with sparse marine fauna and siderite concretions. The total thickness of the Hamilton Group in Pennsylvania runs about 970 feet. In New York State, it thickens from 250 feet near [Lake Erie](/wiki/Lake_Erie "Lake Erie") to over 2,500 feet in [Ulster](/wiki/Ulster_County%2C_New_York "Ulster County, New York") and [Greene](/wiki/Greene_County%2C_New_York "Greene County, New York") counties. Depths ranging from outcrops to 8,000 feet below the surface of [Sullivan County](/wiki/Sullivan_County%2C_New_York "Sullivan County, New York"), in the southeastern part of New York state.

In the interior lowlands of New York and north eastern and north central Pennsylvania, the Hamilton Group contains the [Marcellus](/wiki/Marcellus_Formation "Marcellus Formation"), [Skaneateles](/wiki/Skaneateles_Formation "Skaneateles Formation"), [Ludlowville](/wiki/Ludlowville_Formation "Ludlowville Formation"), and [Moscow](/wiki/Moscow_Formation "Moscow Formation") Formations, in ascending order, with the [Tully Limestone](/wiki/Tully_Limestone "Tully Limestone") above.

These units are divided by the [Stafford](/wiki/Stafford_Limestone "Stafford Limestone"), [Centerfield](/wiki/Centerfield_Limestone "Centerfield Limestone"), and [Tichenor](/wiki/Tichenor_Limestone "Tichenor Limestone") limestones.

In [Ontario](/wiki/Ontario "Ontario"), Canada, the Hamilton Group formations are, in ascending order, [Bell](/wiki/Bell_Formation "Bell Formation"), [Rockport Quarry](/wiki/Rockport_Quarry_Formation "Rockport Quarry Formation"), [Arkona](/wiki/Arkona_Formation "Arkona Formation"), [Hungry Hollow](/wiki/Hungry_Hollow_Formation "Hungry Hollow Formation"), [Widder](/wiki/Widder_Formation "Widder Formation"), and [Ipperwash](/wiki/Ipperwash_Formation "Ipperwash Formation"); the [Kettle Point Formation](/wiki/Kettle_Point_Formation "Kettle Point Formation") of the late Devonian lies unconformably above.

The Mahantango Formation includes these members in descending order: Sherman Ridge, Montebello sandstone, Fisher Ridge, Dalmatia, and Turkey Ridge. In south\-central Pennsylvania, it includes Clearville, Frame, Chaneysville, and Gander Run Members. Its thickness in Maryland ranges from 600 feet in the west, increasing to 1,200 feet in the east, and approximately 1000 feet thick in central Pennsylvania.

The Marcellus Formation contains a local limestones Purcell Member and Cherry Valley as well as [Tioga Bentonites](/wiki/Tioga_Bentonites "Tioga Bentonites") at the base in central and eastern Pennsylvania. Its thickness in Maryland ranges from 250 feet in east, increasing to 500 feet in the west.

The Hamilton Group, [Tioga Bentonites](/wiki/Tioga_Bentonites "Tioga Bentonites"), and [Needmore Shale](/wiki/Needmore_Shale "Needmore Shale") were formerly called the [Romney Formation](/wiki/Romney_Formation "Romney Formation").

* The [Geneseo Shale](/wiki/Geneseo_Shale "Geneseo Shale") is a dark grey to black shale that overlies the Tully Limestone; it includes the Filmore beds.
* The Tully Limestone is a shallow\-water carbonaceous unit.
* The [Moscow Formation](/wiki/Moscow_Formation "Moscow Formation") (Middle Devonian / Givetian) comprises grey to black shales interbedded with limestones and calcareous mudstones and usually bioturbated.

What are some potential implications of the Stratigraphic Setting on human activities or infrastructure development?