FL Geology

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The Finger Lakes Institute presents:: 

The Finger Lakes Institute presents: Mountains, oceans, and rivers of ice: The Geology of the Finger Lakes Region. Eric Primrose Education Outreach Coordinator

The bedrock of the Finger Lakes: 

The bedrock of the Finger Lakes Nearly flat lying (1-3 degree dip to the south) Bedrock outcrops in narrow, east-west bands across the state. Northern outcrops older rock, southern outcrops younger rock

Geologic time in the Finger Lakes: 

Geologic time in the Finger Lakes Exposed bedrock: Mid Paleozoic sedimentary rocks Silurian-Devonian in age No geologic record preserved from late Paleozoic to late Cenozoic Pleistocene age glacial sediments, landforms and landscapes dominate current topography

Silurian Global map: 438-415 MYA: 

Silurian Global map: 438-415 MYA

The Silurian Oceans of New York: 

The Silurian Oceans of New York Much of New York was a shallow ocean during Silurian times Represented a continental shelf on the western border of North America Shallow, tropical ocean- North America roughly 15 degrees south of Equator

Plate Tectonics In New York?: 

Plate Tectonics In New York? Early-mid Ordovician (500-46- mya) Taconic Orogeny creates massive mountains on eastern margin of proto-North America Sediments erode to shallow ocean in the west from Taconic mountains in the east Erosion produces late Ordovician to early Silurian sedimentary rocks in continental shelf basin, including Clinton group NY

Silurian age sediments: 

Silurian age sediments Fine grained clastic and carbonate rocks indicate a shallow ocean environment Sediments deposited from East- Taconic Orogeny Shallow ocean evaporated repeatedly late in the Silurian due to sea level changes, left thick deposits of evaporites during late Silurian (Syracuse formation)

Life in the Silurian oceans: 

Life in the Silurian oceans Include animals such as: Trilobites Brachiopods Corals (Tabulate and Rugose) Cephalopods Crinoids Eurypterids (Sea Scorpions)

Devonian Period: 415-360 MYA: 

Devonian Period: 415-360 MYA

The Devonian oceans of New York: 

The Devonian oceans of New York A shallow inland ocean New York is still in tropical regions Shallow tropical oceans create an environment where carbonates are formed Coral reef communities dominate the fauna of Early Devonian New York

Acadian Orogeny: 

Acadian Orogeny Continued subduction on eastern margin of proto- North America Avalon Island arc collides with continent in Middle Devonian, creating Acadian Orogeny Central and western NY are a shallow inland ocean Erosion of Acadian Mountains create Catskill Clastic wedge. Avalon arc

Bedrock from Late Devonian times: 

Bedrock from Late Devonian times Acadian Mountains erode in the east, producing a wedge of sediments spreading out to the West Catskill clastic wedge produces the clastic sediments that form the middle and late Devonian bedrock of Central New York Deep water environments accumulate thick section of clay muds, producing massive thicknesses of shale bedrock common in Finger Lakes area Later Devonian sediments grow larger in grain size as ocean basin fills with sediment from Acadian mountains to the east

Devonian Life: 

Devonian Life Reef communities are prevalent early in Devonian Animal groups common in the Silurian still predominate Corals (Rugose and Tabulate) Brachiopods Crinoids Trilobites Cephalopods Fish become a important player in ecosystems

The Pleistocene Glaciation: 2 MYA to 14,000 years ago: 

The Pleistocene Glaciation: 2 MYA to 14,000 years ago A period of cooler global temperatures Continental glaciers formed, and advanced across the Finger Lakes region Scoured soil and bedrock from the land, altering the landscape

Pleistocene global map: 

Pleistocene global map

The Finger Lakes before the glaciers: 

The Finger Lakes before the glaciers Before the glaciers came, the Finger Lakes were a series of river valleys, draining the highlands of the north to the Chesapeake bay area to the south.

Glaciers-Continents of ice: 

Glaciers-Continents of ice Increased snowfall and cooler summers create continental ice sheet in eastern Canada As ice sheet thickens, it flows outward due to its immense weight. The ice sheet, almost 2 km thick, bulldozes everything in its path. Finger Lakes soil and sections of bedrock is removed.

Why did the Finger Lakes form where they did?: 

Why did the Finger Lakes form where they did? Shale! The Finger Lakes occupy old river valleys Glaciers dug deep in to river valleys that cut through a thick bed of shale (90 meters) that outcrops in the Finger Lakes region

U-shaped valleys: 

U-shaped valleys Glaciers carved the v shaped valleys of the rivers in the region in to the unshaped valleys that the Finger Lakes now occupy

Glacial features: 

Glacial features The glacier left many other features in the land as they retreated from the Finger Lakes region 14,00 years ago

The bedrock, where exposed, has scratches and gouges in it, oriented roughly North/South These gouges are called striations: 

The bedrock, where exposed, has scratches and gouges in it, oriented roughly North/South These gouges are called striations N

Drumlins: long, skinny hills oriented north/south: 

Drumlins: long, skinny hills oriented north/south N

The sediments in drumlins are a mixed up jumble of rocks and dirt called glacial till: 

The sediments in drumlins are a mixed up jumble of rocks and dirt called glacial till

A boulder or rock that seems out of place is called an erratic: 

A boulder or rock that seems out of place is called an erratic

Long, low ridges, that to run East/West are called moraines. Composed of till: 

Long, low ridges, that to run East/West are called moraines. Composed of till N

Eskers: 

Eskers Long, sinuous mounds of glacial sediments Sediments are sorted Remains of river and streams that flowed on top of, through or under the glacial ice

Kames: 

Kames Small, cone shaped hills Created by cascades of water off the edges or through a hole in the glacier

There are spectacular waterfalls in gorges along the shores of the Finger Lakes: 

There are spectacular waterfalls in gorges along the shores of the Finger Lakes

Hanging valleys: 

Hanging valleys Smaller valley glaciers in tributary streams Eroded smaller valleys Valleys were far above main valley floors, creating water falls.

The Finger Lakes are Gorges!: 

The Finger Lakes are Gorges! Taughannock Falls, Watkins Glen, and Buttermilk Falls all started out as hanging valleys Erosion over the past 14,00 years has worked these hanging valleys back away from the main valley, creating gorges

Glacial Critters: 

Glacial Critters Pleistocene animals include Woolly Mammoth Wooly Rhino Dire wolves Fossil remains are found in bogs, ponds, and glacial till

Human Impact: 

Human Impact Invasive species Industry Mining of geologic riches Increased salinity of Seneca and Cayuga lakes? Draining of marshes and swamps Creation of man-made waterways Ground water usage

Slide33: 

Questions? Eric Primrose Education Outreach Coordinator Finger Lakes Institute

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