New Hampshire Geology New Hampshire Bedrock Map

Paleocene Period
(65-1.8 million years ago)
Formerly known as the Tertiary Period


All Broken Up and Getting Carried Away

The end of the Cretaceous Period, most scientists agree, was brought about by a doomsday asteroid or comet colliding with the Earth.  While this was disastrous for the dinosaurs (they pretty much were wiped off the face of the planet), it opened the door for small, fur covered, warm-blooded, milk producing animals that gave live birth to their offspring - otherwise known as mammals.  This earned the Paleocene Period the nickname "The Age Of Mammals".  As with all of the other "age" nicknames named for an animal type, mammals were not the only animal type in existence, just the most dominant ones.  We (yes, 'WE' humans are mammals too) continue to be to the dominant animal type to this day.

Throughout the last 180 million years, including throughout the entire Paleocene [PAY-lee-oh-seen] Period, weathering and erosion was, and continues to be, going on.  

During the Paleocene Period, the climate of New Hampshire was warmer than it is today.  This warmer climate encouraged chemical weathering through the interaction of water and minerals in the rocks.  For instance, geologists have long known that feldspar, one of the three main ingredients in granite (see"The Recipe For Granite" in the Devonian Period) and the most abundant mineral on Earth, breaks down rather easily in the presence of water, turning into tiny grains of clay.

In addition to the warmer climate, there is evidence that New Hampshire received more precipitation than we do today.  As a result, significant weathering and erosion , or the carrying away of the weathered particles, occured.  While there is plenty of evidence of eroded materials being deposited under water on the continental shelf from Paleocene times, there is very little in the way of Paleocene deposits on land.

This lack of Paleocene deposits is due to the tremendous scouring effects the coming continental glaciers had on the landscape.  The Pleistocene Epoch [PLY-stoh-seen], otherwise commonly known as the Ice Age, marks the end of the Paleocene Period and the beginning of the Neocene Period.

Shaping Up

During the Paleocene Period, the processes that shaped our landscape (the Orogenies and the accretions of exotic terranes) have all taken place.  Only the wearing down of the bedrock (by chemical and physical weathering) and its being carryied away by water, wind and gravity (weathering and erosion ) are at work.  
By the end of the Paleocene Period, our bedrock landscape would be close to today's, with the exception of 1.8 million years more of weathering and erosion .  However, the surface geology would look vastly different than today's because of the upcoming Pleistocene Epoch in the Neocene Period.

Below is a link to an interactive map produced by the United States Geological Survey, or USGS.  It is a map of the bedrock across the United States that you can navigate around by clicking and dragging your mouse cursor.  You can also zoom in and out on specific places.  Check out the difference in the complexity between New Hampshires bedrock and that of Nebraska or Oklahoma.  Why do you think they are so different?  Just click on the image below to try it out.

(Click on the image for a closer look.)
Image Credit: Christopher Scotese;