|An assortment of stones at Kettle Cove,|
including white quartz and gray phyllite
|Arms of dark rock contain the sands of Kettle Cove beach|
|"Petrified wood" is really ocean bottom rock|
split by stretched bands of quartz
The collision with Avalon was prelude to the formation of Pangea. As this is now the coast, we know these impacts were not the end of the story. Africa bumped our coast, and then bounced back out to sea (carrying a piece of Avalon with it). Our "petrified wood" does not have stripes of quartz. It is punctuated by "knots" of it. As the continents split, the bands of quartz stretched. Some parts spaghettified into ribbons. Other sections remained thick with tapered edges. These bulbs, called boudins (French for sausage, which the strands of quartz resemble) become the "knots" in our wood grain.
Inevitably the rock of this formation, having been lain down, rearranged, injected with quartz and stretched, began to break down. Glaciers, rivers and waves have all had their shot at the rocks of the Maine coast, and the most recent of these don't carry rocks very far. The smallest pieces may end up as mud on the ocean bottom or sand on the beach. The larger chunks stay local. The flattened layers become skipping stones. The round quartz knots roll back and forth in the surf. These remnants remain for my son and me to explore while perusing Kettle Cove.
Bentley, Callan. ""Boudinage" is my favorite geology word - Mountain Beltway - AGU Blogosphere." Mountain Beltway Site Wide Activity RSS. American Geophysical Union, 20 June 2011. Web. 19 Aug. 2014. <http://blogs.agu.org/mountainbeltway/2011/06/20/boudinage-favorite-geoword/>.
Berry , Henry N. , and Robert G. Marvinney. "The Geology of Two Lights State Park Cape Elizabeth, Maine." Geologic Site of the Month. Maine Geological Survey, n.d. Web. 19 Aug. 2014. <http://www.maine.gov/dacf/mgs/explore/bedrock/sites/jun02.pdf>.