9/16/2014
TOPOGRAPHIC RELIEF
PHYSICAL GEOGRAPHY:
An Overview of the
Natural Landscape
of New York State
Prof. Anthony Grande
©AFG 0914
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Definitions
GEOLOGIC PROCESSES
Geography: Study of people living on the
surface of the earth.
Geology: the study of the earth and its processes.
TECTONIC (building)
GRADATIONAL
 Folding
 Faulting
 Volcanism
(wearing down)
 Weathering (in place):
mechanical and chemical
 Mass wasting (by gravity)
 Agents of Erosion (with
NATURAL PROCESSES
Geomorphology: the study of landforms.
Mass movements
Earthquakes
Volcanic eruptions
Subsidence
Topography: the study of surface features.
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movement: take-move-place)
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Running water
Moving ice
Wind
Wave action
Long shore currents
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Faulting
Folding
Folded rock layer in the Catskills.
Forces at work:
Compression, bending, breaking
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Lake Champlain, Lake George
Forces at work: movement, and Sacandaga Lake are in rift
tension, breaking
valleys (also called grabens).
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New England Seismic Network
Volcanism
including NYS
Earthquakes occur
throughout NE United
States and SE Canada.
- Two major clusters in
eastern NY.
- One minor cluster in
western NY.
Forces at work: melting, movement of molten material;
eruption can be explosive or gentle.
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Zones of Seismic Activity in NYS
1. LAURENTIAN
ZONE
Earthquakes are caused
by adjustments to the
earth’s surface (rebound)
as tension is released.
US East Coast
Seismic
Hazard
Potential
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NYS
Zone 1
NYS
Zone 3
NYS
Zone 2
3. CLARENDONLINDEN
ZONE
Greatest
2. RAMAPO
ZONE
Source: NYS Museum
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Assessing
Seismic
Risk
Source: USGS 2014
Least
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Recorded Earthquakes in NYS
By County 1973-2012
http://www.dhses.ny.gov/oem/mitigation/docu
ments/2014-shmp/Section-3-7-Earthquake.pdf
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http://www.dhses.ny.gov/oem/mitigation/documents/2014-shmp/Section-3-7-Earthquake.pdf
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Types of Rocks
Types of Rocks
• Sedimentary – Rocks
There are 3 categories
of rocks, each formed
differently, each with
different resistances
to erosion:
Sedimentary
Igneous
Metamorphic
formed by the compaction
of eroded material from
other rocks or precipitates
from dissolved minerals
under pressure from the
weight of successive
layers.
 They make up 75% of the
earth’s surface.
Exposed rocks,
Adirondack State Park
Watkins Glen State Park,
Tompkins Co.
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Sedimentary
Rocks
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Helderberg Escarpment
Catskills
Sediments are laid down in
horizontal layers.
Hudson
Valley
Lowland
Cliff face
The layers are then often
deformed by folding and
faulting or displaced by
volcanic activity.
They are eroded by
running water.
in Ausable Chasm, Essex Co.
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Igneous Rocks
Types of Rocks
Igneous rocks are found at the
surface in three areas:
(1) SE NYS from Staten Island
to Rockland Co. along the
Palisades sill.
• Igneous – Rocks formed by the cooling
and solidification of molten material.
(2) NE NYS in the Saratoga
Springs area where there are
hot springs and pillow lava
formations.
 The rate of cooling determines its crystalline
structure.
 The rate of cooling determines the creation of
minerals.
(Pillow lava is a formation created
when molten rock hits cool water.)
(3) The Hudson Highlands and
Adirondacks contain PreCambrian igneous rock.
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Palisades Sill
Igneous Rocks
Pillow lava at Stark’s Knob, NY >>
Below, recent pillow lava
underwater off of Hawaii.
Sill: a horizontal underground lava flow
intruded between layers of sedimentary rock.
<<Volcanic sill, Haverstraw, NY (Rockland Co.)
related to the Palisades formation.
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Metamorphic Rocks
Types of Rocks
Metamorphic rocks are found
in eastern NYS (Taconic Mts.,
• Metamorphic – Rocks formed by the
addition of great heat and pressure to
existing sedimentary, igneous and
metamorphic rocks.
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Frontenac Arch
(Thousand Is)
Adirondacks
Hudson Highlands and the Manhattan Prong), the Adirondack
Mts. and in the Thousand
Island region (Frontenac Arch).
Taconic Mts.
For example,
shale (sed.) becomes slate
sandstone (sed.) becomes quartzite
limestone (sed.) becomes marble
granite (ign.) becomes gneiss
basalt (ign.) becomes schist.
Hudson
Highlands
Manhattan Prong
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Resistance of Rocks
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Banded gneiss in Adirondacks.
Setting of Niagara Falls
The composition of the rocks give them the
ability to resist forces of erosion.
Igneous and metamorphic rocks are generally
stronger. They are resistant to erosion and form
highlands.
Sedimentary rocks tend to be weaker. They
are found in lowlands.
Together they give us a variety of surface
features and slope angles.
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The Niagara
River drains
Lake Erie.
It flows over the
Niagara Escarpment to reach
Lake Ontario.
In doing so for
12,000 yrs, it has
created a 7 mile
long gorge as
the falling water
eroded weak
layers of rock.
Lake Erie 22 miles upstream of the
Falls.
Moved 7 miles
GORGEin 12,000 yrs
9 miles from escarpment
16 miles from the Falls
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Retreat of
Niagara
Falls
Niagara Escarpment
At the present
rate of erosion it
will take the
Niagara River
75,000 years to
reach Lake Erie.
Horseshoe Falls
American Falls
<< Each layer
of rock has a
different
resistance to
water erosion.
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Niagara Falls
Niagara Falls
American Falls
2011
1969
www.dailymail.co.uk/news/article-1338793/Niagara-Falls-ran-dryPhotos-moment-iconic-waterfall-came-standstilll.html - photos of dry
Niagara Falls in 1969
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Genesee River
Horseshoe or Canadian Falls
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Letchworth State Park
Western NYS
Genesee River
in the “Grand
Canyon of the
East.”
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High Falls on the Genesee River
at Rochester
Landscapes of NYS
NEXT
PALEOGEOGRAPHY
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