Where Does Maine Fit In?
Maine has a very complex geologic story going back at least a half billion years. Much of what you will see in the KMT System are rocks that started forming during the Ordovician Period almost 450 million years ago.
To get a feel for the complex nature of Maine’s bedrock here is a simplified map of Maine’s bedrock formations. Each color represents a different rock type.
It looks a bit like a jigsaw puzzle doesn’t it! How did all of these rocks get assembled!?
400 million years ago, during what geologists call the Ordovician Period, the rocks that make up our beautiful state were located 2500 miles across an ocean in the Southern Hemisphere, separated from what is now North America!! A lot has happened since then! Here’s a short summary:
To quote our state geologist, Robert Marvinney, “several major cycles of deposition, deformation and igneous activity” related to movements of the “plates” that make up Earth’s surface formed the complex geology that exists today in Maine.
Over millions of years, seas and oceans have opened and closed. Sediments deposited under the seas were compressed to form sedimentary rocks. Some rocks that you see along the trails today were originally formed on the floor of an ocean that was a precursor of our present day Atlantic Ocean. (Geologists gave it a cool name – the Iapetus Ocean -because Iapetus was the father of Atlas which is the origin of the name Atlantic!)
An event called the Acadian Orogeny ( mountain building event) compressed, folded and uplifted the rock layers forming mountain ranges. As a land mass called Avalon moved west/Northwestward it closed the existing ocean and in the process incorporated islands and the edge of the western land mass into the uprising mountains. The rocks were no longer flat, but folded and deformed.
During Maine’s Geologic history Volcanic activity at or under the surface formed masses of igneous (fire formed) rocks. Extreme heat and pressure within the earth has transformed both igneous and sedimentary rocks into metamorphic rocks. These processes continue today, slowly but surely changing our state and planet. You will see evidence of these changes in the rocks on the trails.
But there’s more! In the more recent past, only 10-15,000 years ago, Maine experienced glaciation. A mile thick ice mass covered the state as well as much of what is now Canada and the Northern tier states. The weight of all of this ice depressed the land, allowing the sea to move farther north. The coastline of Maine reached as far north as present day Millinocket. As the glacier melted back it both carved and shaped the surface and deposited lots of material such as sand and gravel and soil known as glacial till, not to mention very large boulders (erratics) that are seen all over the state.