Maine Geology

Maine Geology


Visual evidence of the role which the laws of physics played in the formation of the Earth appears in many locations in the State of Maine. Early on much of the Earth consisted of plates formed by sedimentary processes. As the plates separated through seafloor spreading various configurations appeared. There is convincing evidence that about 260 million years ago Europe collided with North America. Other continents merged so that most of the dry land mass of the earth was grouped into one super-continent named Pangea.  The preceeding as well as most of the material to follow is taken from Caldwell, D. W., 1998.

Separation of the continents began and the oceans began to form about 200 million years ago. The North American plate was forced westward, driven by hot magma emerging from the mid-ocean ridge. The emergence of hot magma at the separation ridge produced basalt which was quenched by the cooler ocean water. The westward moving plate moved over the top of another plate and the high pressure and friction at the interface generated volcanic activity as well as the mechanism responsible for the reformation  of new material formed at high temperatures and pressures. These pressures forced buckling of the plates as well as upheaval where the previously horizontal plates could become tilted or, in some cases, inverted.

Finally, the great continental glaciers covered much of North America from 40,000 to 18,000 years ago. Maine was covered until 12,000 years ago.

The contribution of basalt is that it apparently formed from quenching of the liquid magma in both water and molten granite.  In either case, the basalt solidifies to form a pillow shape. Hence, the name basalt pillow.   Photo IMG_1930.jpg (in the folder Bucksport Geology) shows basalt pillows lined up along the Marginal Way in Ogunquit. Most likely these were moved to this location to line the walkway. The link reports other basalt pillows along the Northeastern coastline. Smaller examples of basalt pillows are shown in IMG_1909.jpg. These were found at different locations in the mountains near Rangeley, approximately 150 miles to the Northwest. Caldwell reports that large basalt pillows also are found at Jim Pond formation in the Alder Stream Township near Rangeley. The similarity of the shapes seen for rocks found at these different locations indicates that these individual pillows may be single grain, much like quartz. The shape is a function of the crystallographic structure.

Evidence of the upheaval is shown in the photo Newcastle1A.jpg. Just at the middle of the picture is an apparent peak of a convex bulge, as could be caused by plate buckling.  Geologists call this an anticline. Note the approximately horizontal layers to either side of the bulge. This was taken along Highway 1 at Damariscotta/Newcastle, Maine, which is on the coast.

An idea of the dramatic events unfolding in the formation  of the surface layers of the Earth can be seen in the photos IMG_1883.jpg to IMG_1893.jpg. These were taken where a new cut was made through the rock, to accommodate the approach to the new bridge across the Penobscot River. Most striking is IMG_1886.jpg. One can imaging a time in the formation when the diagonal veins of white granite were not there. Then, in one dramatic moment, a crack occurred in the structure containing the molten granite below, and the granite shot up under high pressure, fracturing the rock at approximately 45 degrees, forming the dike shown in the face of the cut. Shear cracks such as seen in brick houses typically flow at 45 degrees. Further, the wider opening of the crack at the top is consistent with crack behavior in other materials. Deep in the solid, the full hydrostatic strength of the material resists the fracture from the granite. Hence, the crack is narrow. Toward the surface, however,  the hydrostatic strength of the host rock is lessened by the surface, causing the crack to open wider as the fluid, molten granite emerges.

There are probably are other features here that a real geologist would  find interesting and be able to identify.  I would like to receive any further information on these features.

Final evidence of the dynamic events in the formations is the wavelike actions seen in the photos Pemaquid 1-3.jpg. Here much of the mudstone and sandstone has been washed away by constant wave action over the years.  And, the formations that are now laying down were at one time vertical. But, the feed of the granite into the original structure here reveals a condition not seen in the other areas.

The wavelike patterns of the granite are significant. Note the somewhat uniform distance between the crests and valleys of the granite at the top. It is easy to visualize a time when this structure was more vertical and the granite vein was not there. If the mudstone and limestone were at very high temperatures, being almost liquid, and under high pressure, the rapid intrusion of the molten granite could behave much like a flickering flame or the stream of one fluid being injected into another with different densities. The whipping back and forth of the flow would be a function of the densities of the two materials, as well as the speed of the flow.

Basalt pillows are formed under the sea bed by lava flow erupting into cold sea water.

Video of pillow formation off of Hawaii

Observations such as these reinforce the idea that the laws of physics (and chemistry) have existed in the Earth throughout its history. Movement of mountains and seas et al. are easily explained using these physical laws.

In conclusion, I need to observe the obvious, I am not a geologist, merely a rock collector with a scientific background. While I believe these observations are valid, I am always open to clarification and correction by persons more knowledgable in the field than I.

For further reference:

Caldwell, D. W., Roadside Geology of Maine, Mountain Press  Publishing Company, Missoula, Montana, 1998.

Bucksport is one of the significant geological formations along the Maine coast. Most of these observations were obtained there, hence is he title for these files.

Photos and text Copyright Don E. Bray 2006. Permission to use for personal or educational purposes is automatically granted with proper acknowledgment of the source.