Table 1 - Simplified Geologic History of the New York City Area

Geologic	Radiometric	Stratigraphic/	Original Rocks or Sediments	Geologic Event
Period	Age in m.y.	Rock Unit
Pleistocene		Glacial detritus	Till, sands, clay	Continental glaciation, leaving moraines and outwash plain
Cretaceous to Tertiary		Coastal Sediments	Sands, clay, and conglomerate	Shallow marine deposition on continental shelf
Jurassic	200	Newark Series,	Red sands, shales, and conglomerates	Rift-basin formation and basaltic volcanism related to
Triassic		Palisades diabase	basalt, diabase	extension; eventually, the opening of the Atlantic Ocean
		Unconformity		100 million years of erosion
Devonian	380	Two-mica granites		Acadian orogeny, here expressed by intrusion of many small
	(Stops 3, 4, 5)			two-mica tourmaline granites, shearing, and retrogressive
				metamorphism at about 550° C and 20 km depth
				Produced muscovite schist and tremolite marble
				Uplift and erosion
Ordovician	~445	Anatectic granites		Late phase, Taconian orogeny: upright folding, intrusion of
	(Stops 3,5)			granites, metamorphism at peak
				temperatures (>850°C) but reduced pressure (~26 km depth)
--------------------	(Stop 5)	Hartland formation,	Island Arc volcanic rocks and associated	Emplacement of ophiolite (serpentinite) and exotic Hartland
		serpentinite	well-bedded shales, sands, and	island-arc terrane over (deformed) North America
			minor limestone, and ultramafic rocks
	~450	Anatectic granites		Early deformation, Taconian orogeny- Thrust faulting- Slices
				of Neoproterozoic rock emplaced over younger Walloomsac;
				high-pressure metamorphism (>40 km depth)
				and granitic intrusion (due to melting of crust)
Ordovician		Walloomsac Schist	Sulfidic, carbonaceous shales, sands,	Deposition in a narrow basin, which deepend as the exotic
			and minor limestones	Hartland volcanic arc terrane impinged on North America
		Unconformity
Cambro-Ordovician (Stop 2)		Inwood Marble	Dolomite, limestone, minor siliceous beds	Shallow marine deposition, continental shelf (carbonate bank)
		Unconformity
Late	(Stop 1)	Ned Mountain	Bimodal volcanic rocks; sands, limestone,	Rift-basin deposits and bimodal (mafic/felsic) igneous activity
		formation	minor conglomerate, shale	record lithospheric extension, which prompted
Neoproterozoic	~560	(inc. Yonkers gneiss)		the birth of the Iapetus Ocean; deposits range from
				terrestrial/shallow water (Yonkers gneiss member,
	(Stop 3)	Manhattan Schist	Sands, shale, basalt	Ned Mountain fm.) to deeper water (Manhattan Schist)
		& "Bronx Zoo-type"
		strata
		Unconformity		400 million years of erosion
Middle	1000 to 1200	Fordham Gneiss	Subduction-related volcanic and plutonic	Grenvillian orogeny; high-grade (granulite-facies)
Proterozoic	(Stop 4)		rocks with minor sediments; mafic bodies of varied origins	metamorphism, granitic intrusion, deformation; Volcanic arc activity