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Adirondacks
by Megan Capeless
Physical Geology
Spring 2008         
                                                     The Adirondacks

In New York State, the upper northeast region is referred to as the Adirondacks, this region has over 3,000 lakes, 30,000 miles of running streams, 8,000 foot mountains, and takes up six million acres of New York State. This region is larger than the Grand Canyon, Yellowstone, and Yosemite all combined; the dimensions are 144 by 93 miles, an area of 13,392 square miles; 26 percent of New York State.


 

www.adkscience.org/adirondacks.htm
 

            This region is well-known to all New Yorkers and east coast residents; because of its exciting summer and winter activities, beautiful scenery, and of course the geological history of the mountains.
 

Lake George, New York

http://www.tubbytubestubing.com/lakegeorge.cfm
 

            But where did this mysterious mountain region come from? Contrary to popular belief it is not an extension of the Appalachian chain; but part of the Precambrian Shield. The Adirondacks were formed under 15 miles of overlying rock and over time the rock began to uplift, in fact this process is still happening today about 2 to 3 millimeters every year.
 

http://www.lakegeorgeassociation.org/html/geology.htm

The Adirondacks are young mountains, but they are made up of the oldest rocks on the planet. This means that the soil and rocks we see today, that were under 15 miles of overlaying rock, formed around one billion years ago; the sediment that was built up from an ancient sea was forced lower and lower by
more sediment, until it metamorphosed under high temperatures and pressure.



This picture shows the oldest Precambrian rocks in the United States and if you look at New York the big yellowish orange spot is the Adirondacks.

http://tapestry.usgs.gov/ages/precambrian.html
 

            The majority of the rocks in the Adirondacks are made up of metaplutonic rocks, which include granitic gneiss, metanorthosite, and olivine metagabbro. Granitic genesis is the most common rock; it is a metamorphosed plutonic rock, which is composed largely of alkali feldspar and quartz.
 

http://www.earthscienceworld.org/images/search/results.html?Keyword=Gneisses
 

Metanorthosite forms several large bodies in the Central Highlands. It is an unusual rock, composed of a single mineral type, plagioclase feldspar. It is similar to the rock that is on the Moon.
 

http://apod.nasa.gov/apod/ap040121.html
 

Olivine metagabbro is less abundant than granitic gneiss and metanorthosite, but numerous masses of this rock are scattered throughout the eastern and southeastern Adirondacks.
 

http://instruct.uwo.ca/earth-sci/fieldlog/cal_napp/eclogites/oph_eclogite.htm

 
References

http://gorp.away.com/gorp/resource/statepark/ny_adiro.htm

http://www.nywea.org/clearwaters/04-1-spring/adkhist.cfm

http://www.adirondack-park.net/history/geological.html

http://gretchen.geo.rpi.edu/roecker/nys/adir_txt.html

http://www.adirondacks.com/adkhistory.html

http://tapestry.usgs.gov/ages/precambrian.html