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- Hofstra
The Geologic History of New York State The Taconic Orogeny Cambrian - Ordovician Geology Ontario, Mohawk, Hudson, Wallkill Lowlands Taconic Mts. Manhattan Prong Cambrian - Ordovician Geology NE SW Helderberg Escarpment Niagara Escarpment Tug Hill Plateau Adirondack Dome SW NE Cambrian-Ordovician Stratigraphy Western NY Lower Cambrian Potsdam Sandstone Lower Cambrian Potsdam Sandstone, Ausable Chasm, New York Upper Cambrian Hoyt Limestone, Saratoga Springs, New York Stromatolites Stromatolites Middle Ordovician Limestone, Watertown, New York Upper Ordovician Utica Shale, Mohawk Valley, New York Upper Ordovician Greywacke and Shale, Tug Hill, New York transgression Simplified Stratigraphy of Western New York Upper Ordovician Deep Basin Lower and Middle Ordovician Shallow Shelf Cambrian Beach Lorraine Shale Utica Shale Beekmantown, Trenton, Black River Limestones Active Margin Passive Margin Potsdam Sandstone unconformity Proterozoic Adirondack metamorphic rock Cambrian-Ordovician Stratigraphy Eastern NY Lower Cambrian quartzite Grenville Gneiss Proterozoic nonconformity - southeastern NY Lower Ordovician Wappinger Group dolostones, S.E. New York Upper Ordovician Normanskill Greywackes, Wallkill Valley, New York transgression Simplified Stratigraphy of Western New York Middle to Upper Ordovician Deep Basin Lower Ordovician Shallow Shelf Cambrian Beach Active Margin Normanskill Shale and Greywacke Wappinger Group Dolostones and Limestones Passive Margin Poughquag Quartzite unconformity Proterozoic Grenville metamorphic rock Cambrian-Ordovician Stratigraphy Southeastern NY High Grade Metamorphism Manhattan Prong - high grade metamorphism • Manhattan schist, Inwood marble, Hartland gneiss • Deeply buried during metamorphism. • Roots of a high mountain range. Inwood Marble (450 million years old) Fordham Gneiss (1 billion years old) Metamorphic Rocks of Manhattan Inwood Marble East bank of the Hudson R. Manhattan Schist / Hartland Gneiss (450 my) Inwood Marble (450 million years old) Fordham Gneiss (1 billion years old) Metamorphic Rocks of Manhattan Manhattan Schist, Central Park Manhattan Schist Hartland Gneiss and igneous intrusion Orchard Beach, Bronx Cambrian-Ordovician Stratigraphy Southeastern NY Low Grade Metamorphism Taconic Mountains - low grade metamorphism • Slates and phyllites • Thick pile of sediments shoved westward. • Taconic rocks are allochthonous (out of place). • Klippe - large region of allochthonous rock. Evidence for the Upper Ordovician Taconic Orogeny Eroded sediments from eastern mountains deposited in a deep basin Sh ov ed cr us t Metamorphic roots Taconic Orogeny • Collision of North America with a volcanic island arc. • Middle to Late Ordovician • First orogeny caused by the closing of the Iapetus Ocean basin (also called “protoAtlantic”). Taconic Mountain Building Event (450 million years ago) Taconic Mountain Building Event (450 million years ago) Shale and Greywacke Marble and Mica Schist Amphibolite and Gneiss Taconic Mountain Building Event (450 million years ago) Bedrock geology of the southern Manhattan Prong. Cameron’s Line - the suture line between metamorphosed rocks of ancient North America and metamorphosed rocks of the Taconic volcanic arc. 0 Ma Phanerozoic Modern Geologic Time Scale C M P Pliocene Neogene Tertiary Pleistocene Paleogene Cenozoic Proterozoic Miocene Oligocene Eocene Paleocene Cretaceous Mesozoic 2500 Ma Holocene Quat. 540 Ma Jurassic Triassic Archean 3800 Ma Carb. Paleozoic Permian Pennsylvanian Mississippian Devonian Silurian Ordovician Cambrian Ma 0 .01 1.6 5 23 35 57 65 146 208 245 290 323 360 408 439 510 540 Hadean 4600 Ma Quat. = Quaternary Carb. = Carboniferous Taconic Orogeny Passive margin Silurian Geology Appalachian Fold Belt Shawangunk Ridge Wallkill Valley and the Gunks, New York Shawangunk Ridge, near New Paltz, NY Shawangunk Conglomerate, New York Cement mine in Upper Silurian carbonates, eastern New York Taconic Angular Unconformity Lower Devonian Upper Ordovician Upper Silurian Upper Silurian carbonates Ordovician shale and sandstone Taconic Angular Unconformity transgression regression Simplified Stratigraphy of Eastern New York Lower Devonian Tidal Flats Shallow Shelf Manlius dolostone Passive Margin Rondout limestone Late Silurian Shoreline Shawangunk Conglomerate Angular unconformity Ordovician Uplifted shales and siltstones After the Taconic Orogeny • Taconic Mountains erode. • Collision uplifts previously deposited strata. • Angular Unconformity is created. • Silurian - sea level rise floods unconformity surface. • Shawangunk conglomerate and sandstone deposited. • Upper Silurian carbonates (limestones and dolostones) deposited. • Lower Devonian carbonates deposited. 0 Ma Phanerozoic Modern Geologic Time Scale C M P Holocene Miocene Oligocene Eocene Paleocene Cretaceous Mesozoic 2500 Ma Pliocene Neogene Tertiary Proterozoic Pleistocene Paleogene Cenozoic Quat. 540 Ma Jurassic Triassic Archean Carb. Paleozoic Permian Pennsylvanian Mississippian Devonian Silurian Ordovician 3800 Ma Cambrian Ma 0 .01 1.6 5 23 35 57 65 146 208 245 290 323 360 408 439 510 540 Hadean Quat. = Quaternary Carb. = Carboniferous 4600 Ma Silurian Geology Niagara Frontier Ontario Lowlands Lake Ontario Niagara River Lake Erie Passive margin Taconic Orogeny Passive margin Ontario Grand Island Silurian Rock New York Nia gar aE sca rpm ent Niagara Falls Ordovician Rock Silurian Rock Ordovician Rock N Late Silurian limestones and shales Niagara Gorge Horseshoe Fall, Niagara NY American Falls and view up-river (south) Canadian Falls