The Finger Lakes Institute presents:

1
The Finger Lakes Institutepresents

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

2
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

3
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

4
Silurian Global map 438-415 MYA
5
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

6
Plate Tectonics In New York?
NY

• 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

7
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)

8
Life in the Silurian oceans

• Include animals such as
• Trilobites
• Brachiopods
• Corals (Tabulate and Rugose)
• Cephalopods
• Crinoids
• Eurypterids (Sea Scorpions)

9
Devonian Period 415-360 MYA
10
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

11
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
12
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

13
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

14
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

15
Pleistocene global map
16
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.

17
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.

18
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

19
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

20
Glacial features

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

21
The bedrock, where exposed, has scratches and
gouges in it, oriented roughly North/SouthThese
gouges are called striations
N
22
Drumlins long, skinny hills oriented north/south
N
23
The sediments in drumlins are a mixed up jumble
of rocks and dirt called glacial till
24
A boulder or rock that seems out of place is
called an erratic
25
Long, low ridges, that to run East/West are
called moraines. Composed of till
N
26
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

27
Kames

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

28
There are spectacular waterfalls in gorges along
the shores of the Finger Lakes
29
Hanging valleys

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

30
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

31
Glacial Critters

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

32
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

33
Questions? Eric Primrose Education Outreach
Coordinator Finger Lakes Institute