APES- its descent, and ground up native
120,000 years ago ice began to form at a rapid pace in northern
Canada(Grette, www.biomass.umass.edu). This sheet quickly (on a geologic
scale) swept down the eastern seaboard and engulfed the northeast down to
present day Long Island, New York in a sheet of solid ice. This ice-sheet
later in history became known as the Laurentide ice-sheet, named after the
region in Canada in which it made its descent(Oldale,
http://pubs.usgs.gov). Little did anything know back then that it would
have had such a profound impact on a region as it did on the northeast.
Particularly in Massachusetts’ case we owe the ice-sheet for giving it the
distinctive “flexed armed” appearance we see with Cape Cod jutting out into
the Atlantic Ocean. This formation was created by the active Laurentide
sheet approximately 14,000 years ago(Pinet, 1992). The advancing ice-sheet
brought and pushed sediment that has created the Cape Cod peninsula. This
glaciation of the area brought huge boulders and rocks down from Canada on
its descent, and ground up native rocks and gravel to sand and sediment.
After reaching its furthest extent about 10,000 years ago, and has long
began its retreat. It had left behind all the rocks, sediment, and debris
locked in its frozen vaults. After it had completely left the area, behind
it was the recessional moraine, Glacial Cape Cod Lake. As the glacier fully
receded water levels rose, filling in an area of about 3 miles of shore
once a part of Massachusetts, and consequently filling in the glacial lake.
Resulting from the receding Laurentide Ice-sheet, many new minerals and
rocks were deposited on the area that have never been seen here before. The
bedrock was formed in the late Precambrian and Paleozoic eras, and is made
up of crystalline igneous and metamorphic rocks. So, these have been here
all along. Glaciers in the Pleistocene and Holocene eras, deposited many
sedimentary(eastern Mass.), igneous(middle/eastern Mass.), and metamorphic
rocks(eastern/middle Mass.) throughout the state.
These deposits (most prevalent sedimentary) are found along the coast of
eastern Massachusetts and makes up the entire arm of Cape Cod. This may not
seem like such a big deal, however the Till made of Pleistocene and
Holocene sediments is a very loose and grainy type. Though this sediment
helps make the Cape a wonderful beach area, it may lead to its demise as
well. In some areas of the Cape may erode bluffs 10-15 feet in a 2-7 period
of time(www.whoi.edu). Many of these problems have been magnified my human
occupation and alteration of the shoreline.
Today, the innovative species we are, have taken this material brought to
us on a proverbial flying carpet and made a business out of it. Many of the
rocks mined throughout Massachusetts are used as building materials,
gravel, and sand. Though this may seem petty, it is a very lucrative
business and the state makes a lot of many though exporting natural
minerals and rocks.
In the state of Massachusetts mineral, stone, and steel exports make the
state over a one hundred-million dollars annually and employ thousands of
workers in mines, processing plants, and excavation. On the states list of
the top 97 exports six of them involve the geology of the state directly
while others also are connected, yet indirectly. On that list ranks base
metals(23), aluminum(26), stone for art purposes(38), copper(39), salt and
sulfur(61), and mineral fuel(67).
Ancient Massachusetts was a very different place than it is today. Once
covered by a huge glacier only 13,000 years ago, now has one of the most
recognizable coastlines on the eastern seaboard. Massachusetts has truly
been molded by the glaciation of the past. What remains of that giant sheet
now helps our economy run(somewhat) smoothly, our citizens to enjoy the
beaches, and a distinctive land formation, that is Cape Cod.