Be extremely careful near the cliffs, people have been swept off the rocky shoreline by rogue waves. Rocks may be slippery.
Schoodic Point is a peninsula of granite. The granite is light gray with a slight pink tinge. Cutting through the granite are dikes of dark diabase. Granite and diabase are both igneous rocks that form from the cooling of magma. The USGS has a good set of graphics on their website.
At Schoodic Point, the granite was formed first as one large mass. Fractures formed in the granite were later filled by molten rock (magma). The magma cooled quickly to form the diabase dikes.
As you walk over the rocks you can find examples where the granite on opposite sides of a dike would fit together like puzzle pieces if they were not separated by the diabase. There are also pieces of granite broken off from the sides of the fracture that were frozen in the middle of the dike. A very close examination of the edges of some of the dikes shows streaks that formed in the flowing magma.
You can also find examples of the different strengths of the diabase and granite. Find a spot where a dike extends into the ocean. (Again, don’t go any farther than is safe.) The harder rock erodes more slowly and extends farther into the ocean.
Send me an EMAIL, (not a message) via the user profile link above with the following information :
- The text "GCZ5FP Diabase Dikes – Schoodic Point, Acadia NP" on the first line
- The number of people in your group and if anyone is logging separately, their login name(s).
- Compare the relative hardness of the two types of rocks at Schoodic Point based on how easily they are eroded by the waves.
- What is the name of the primary granite found on Mt Desert Island and compare it with the granite found on the Schoodic Peninsula?
- Measure the width of the dike (smaller one) at the coordinates and measure the width of the other wider dike close by. If you are physically unable to reach the coordinates, estimate the width of one of the more accessible dikes and provide me with the coordinates where you took your measurement.
- Optional: Post a photo of you and your GPS at one of the other dikes at Schoodic Point
Be sure to check the box to include your email address with your answers so that I can send you the OK to log. Any logs posted before I receive your email and qualify your find or logs containing spoilers will be deleted without prior notice.
The above information was compiled from the following sources:
- -Maine Geological Survey, Department of Conservation, Basalt Dikes at Schoodic Point, Acadia National Park, http://www.state.me.us/doc/nrimc/mgs/explore/bedrock/sites/nov04.htm, last updated 10/6/2005
- -Gilman, Richard A., Carleton A. Chapman, Thomas V. Lowell, Harold W. Borns, Jr., The geology of Mount Desert Island A Visitor’s Guide to the Geology of Acadia National Park, Maine Geological Survey Department of Conservation, 1988
- -National Park Service, Acadia National Park, Geologic Database to accompany digital geologic maps, acadglg.hlp, version 2004-02-02; 16:11 MST
This is a National Park Service-approved earthcache site. The information here has been reviewed and approved by the Acadia National Park staff. Thanks to the staff for their assistance.