Transcript Voyageurs National Park

Voyageurs National Park
by Megan Saunders
http://www.nature.nps.gov/geology/inventory/publications/reports/voya_gre_rpt_view.pdf
Voyageurs National Park

Interest in protecting the area
since 1891
Established as
a national park
in 1975
 Named for
historic
FrenchCanadian
voyageurs

Location of Voyageurs
http://nps.seeamerica.org/maps/mn.gif
Voyageurs National Park
http://www.us-national-parks.net/images/voya.jpg
Geologic History of Voyageurs
Contains some of the oldest rocks in
North America (Archean aged)
 Algoman Orogeny

– Formed by repeated collisions of
isolated areas of crust
– Subduction created volcanic island arcs
– Later in Orogeny, intrusion of granitic
plutons
Geologic History of Voyageurs
 In
the
Proterozoic,
isolated crustal
regions
accreted into
one large craton
 Voyageurs on
Canadian Shield
http://www.kettlefallshotel.com/aerilalake.jpg
Geologic History of Voyageurs
 Craton
covered
by inland seas
in early
Paleozoic
 Exposure and
erosion during
late Paleozoic,
Mesozoic, and
Cenozoic
http://www.destination360.com/north-america/us/minnesota/images/s/voyageurs-national-park.jpg
Geologic History of Voyageurs
 Glaciations
in Pleistocene
– Most recent ended about 10,000 years
ago
 Glacial
scouring
– Lake formation
– Glacial striations
– Polishing
 Glacial
deposits
– Lake formation
– Till and moraine deposits
http://www.usatravelpal.com/images/states/minnesota/voyageurs-national-park.jpg
Stratigraphic Column of Voyageurs
Archean
http://www.ux1.eiu.edu/~cfrbj/parks/voya/Voyastarcol4.pdf
Current Geology of Voyageurs
 Superior
Province
– Sub-provinces:
 Wabigoon
Sub-province
 Quetico Sub-province
 Wawa Sub-province
– Fault Zones:
 Rainy
Lake-Seine River
Fault Zone
 Vermillion Fault Zone
http://www.nature.nps.gov/geology/inventory/publicati
ons/reports/voya_gre_rpt_view.pdf
Current Geology of Voyageurs
 Erosional
and glacial evidence
– Flat landscape
– Thin soils
– Glacial erratics
http://www.nps.gov/voya/index.htm
References
American Park Network.
http://americanparknetwork.com/voyageurs
Geologic Resource Evaluations.
http://www2.nature.nps.gov/geology/inventory/gre_publica
tions.cfm
Harris, A. G., E. Tuttle, and S. D. Tuttle. 2004. Geology of
National Parks (6th edition). Kendall Hunt Publishing
Company, Dubuque, IA, 882 p.
Kiver, E. P. and D. V. Harris. 1999. Geology of U.S. Parklands
(5th edition). John Wiley and Sons, Inc., New York, NY, 902
p.
NPS Explore Geology.
http://www2.nature.nps.gov/geology/tour/
USGS Geology of National Parks.
http://wrgis.wr.usgs.gov/parks
Rocky Mountain
National Park
Emily VanWyk


Rocky
Mountain
National Park
(ROMO) was
established
January 26,
1915 with the
passing of the
Rocky
Mountain
National Park
Act
In 1976 the
park was
designated a


ROMO is located in the North-Central part of
Colorado on the Front Range
The Front Range is on the Continental Divide,
and is the furthest east part of the Rockies
Called the “roof” of the
Rockies, as the some of the
highest peaks in the Rockies
are found here, including a
Handful over 14,000 feet above
sea level.

Basement Crystalline Rocks
Precambrian
The oldest rocks are Precambrian, deposited
approximately 1800 million years ago in a marine
environment.
Shale, sandstone, and carbonates, were interbedded with
volcanics.
Once lithified, these were metamorphosed into crystalline
schists and gneisses which were intruded by massive
granitic magma during mountain building.
Late Precambrian was a long, intense period of mountain
building and regional metamorphism from intrusions
Silver Plume Granite
Precambrian



A huge batholith, 30 miles across, emplaced itself within
these gneisses and schists. This is the Silver Plume granite,
and outcrops in much of the eastern side of the park.
This granitic batholith contains radioactive materials which
allow for precise dating. The formation was intruded 1450
million years before present.
http://www.cliffshade.com/colorado/rmnp/rmnp01.jpg
Creation of Ancestral Rockies
The Paleozoic
Precambrian uplands were eroded, and
Paleozoic seas moved over what is now
the park. Marine sediments were laid
down.
 The region uplifted in the Pennsylvanian,
creating the Ancestral Rockies.
 These were soon leveled by erosion in the
Mesozoic when seas transgress.

Laramide Orogeny
Cretaceous
 The
Cretaceous marks the last
time the sea advanced on the land
in the park.
 North
America plate and Pacific
plate collided at the end of the
Cretaceous, leading to differential
compression, fault blocks, and
thrust-faulting.
Creation of the Front Range
Tertiary
More uplift, erosion, and volcanism.
 Uplifts primarily along old faults, elevation
increased. Front Range rises as a series of
steps
 Movement possibly due to isostatic
compensation.
 By Quaternary, the Front Range as we
know it in height was in place.

The Front Range illustrates thrust faulting and folding, as
well as huge, faulted anticline mountains. High angle
thrust faults created these features, along with isostatic
adjustment. There are major faults on both sides of the
range. Extensive activity shows the park is found on the
leading edge of the continent.
It is hard to understand the formation of the Rockies, as
they are located far inland, far from the tectonic
boundary.
Most geologists think they were created by an extremely
low angle subduction, which let crust push under the
continental crust all the way inland to push up the
mountains.
Extensive thrusting built up the huge mountains.
Glaciation
Pleistocene
Early glaciation included two main
advances 1.2 million years ago.
Most traces of these glacial advances
were destroyed by later glacial
periods. The oldest evidence can be
found on the eastern boundary of the
park.
Glaciation
Pleistocene
Bull Lake Glaciation, brutal and long lasting,
occurred between 300,000 ybp and
130,000 ybp.
This glacial period deepened basins created
by earlier glacial periods, and left
prominent moraines.
These moraines are very close together,
indicating a slow retreat speed. They are
similar in size, shape, and type of
material.
Can be found near Shadow Mountain Lake,
Beaver Meadows, and Moraine Park.
Glaciation
Pleistocene
Pinedale Glaciation occurred during
Wisconsonian time. This included three
episodes which reached their maximum
approximately 20,000 to 18,000 years
ago.
 Sculptured the mountains as we know
them, making strong ridges and steep
drop offs. This period is responsible for the
nearly vertical east face of Longs Peak.
 This period was much less intense.
 The last Pleistocene Glacier disappeared
about 10,000 years ago.

Post Pleistocene Glaciation
 Neoglaciation
began about 3,800
ybp.
 Two major advance/retreat series
known.
 Currently, there is little more than
perennial snowfields and glacierets.
These have recently increased in size
Glacial Features
Rock-Basin Lake - Cub Lake, East Inlet
 Moraines - Moraine Park
 Roche Montonnee - Glacial Knobs
 Glacial Pavement - North Inlet
 U valleys - Fall River
 Cirque
 Hanging Valley - Hanging Valley

Sources
 usgs.gov/parks