Millions of years ago two continents collided to form a new area, which is now the East Coast of the United States. North America and Avalon slowly moved together creating a slip fault between them. Large amounts of volcanic sediments were deposited between the two continents both from Avalon and North America somewhere between 40-50 million years ago. As the continents continued to collide at an angle to one another they created a right lateral slip, which there is evidence of throughout the eastern part of Maine.
The sliding that has taken place since this event has caused pressure beneath the surface which has resulted in major folding events, such as those seen at Twitchell Corner. At this site, after the formation of the graded beds, large glacier events took place which caused shearing. This form of glacial weathering occurs in a general North-South direction and is apparent from scratches across the rock as well as large amounts of erosional unconformities throughout the area.
For more detailed information on both the history of Twitchell Corner and the major geological features of the area, click on any one of the topics below.