Saturday, January 03, 2015



Petroforms are boulder outlines on the ground, often representing turtles, snakes and animals, and some of the most famous examples are at Tie Creek in Manitoba, which Jack Steinbring mapped years ago when he taught at the University of Calgary.

We have petroforms here in New England, but many go unnoticed because they are flat on the ground.  One of the more interesting examples I have come across is in Hopkinton, RI, in a cedar grove with moss and lichen covering the granite bedrock. 

Petroform is on the ground in the middle

A close-up view of the petroform showed that the stones were well seated in whatever soil covered the bedrock, and were in turn covered with lichen.  To me, this indicated that the petroform had been in place probably when the bedrock was fully exposed.  In other words, the feature was ancient, and perhaps thousands of years old.

The petroform was then mapped with a grid, and the results are here:

Although it is not clear by the drawing what the petroform resembles, the close-up photo, above, seems to represent a turtle.  Near this petroform, and in the same type of terrain, is a large flat-topped stone mound constructed on a low outcrop.


Bob Miner found another petroform in a dry vernal pool at the Carter Preserve in Charlestown, RI, which seems to represent another turtle. Larry Harrop photographed it: 


Nearby in the same vernal pool was a wedged split boulder.  When Larry removed the thick moss covering the split, the wedged rocks became visible.


The question remains, when were these stone features created?  Certainly they must have been made when the pool was dry or perhaps before the vernal pool was formed.  In any case, both features look ancient.

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