South Watuppa Pond Grinding Slicks

In the past two months, I have shown several stone row sites along the shoreline of South Watuppa Pond.  The stone rows have propped boulders, manitous, and effigies, suggesting they were constructed by Indians.  Some of them may have been campsites, and some have smaller features suggesting their uses.
Here is one site on the Fall River shoreline, south of the state boat ramp (Dave's Beach).

This stone row projects north from a small peninsula, and forms a small enclosure. Here is the  propped boulder at  the end of the wall.

Inside the enclosure is this large  rock with a  smooth, slightly concave top surface. The water inside the enclosure is less than a foot deep, so it would have been dry land before  the pond was raised in 1826.

  Similarly, next to the turtle effigy boulder (7/11/2012) further south along the shoreline is this rock with a squarish depression.

These may have been grinding slicks that were used for grinding acorns or edging tools.  These are shallow and irregular, in contrast to the round and deep mortars used for corn.  It is interesting that this one is close to an effigy, suggesting a ceremonial use.
     Here is a large flat boulder with two depressions at Cranberry Neck. The water around it is only two feet deep, so it would have been out of the water before 1826. The rocks in the background are part of the stone row that extends to the rocky little island (7/18/2012).

The smooth, concave surface  of the smaller depression suggests grinding.   Those are freshwater clam shells in the larger depression.  This is now a lunch spot for muskrats and mink.

     Here is another possible grinding slick, from along the east shore.  Notice that there appears to be a "gutter" to the left in the stone, similar to the large stone shown 9/23/2011. There aren't any other structures close to it, but the area was farmed and then developed for camps and cottages.
     Finally, here is a large flat stone near the west shore stone row shown 6/13/2012. The water is less than a foot deep here.

From this angle, it does resemble a turtle.  However, inspection of the top from the other side shows this 6 inch deep depression, also with a "gutter".  If this was used as a grinding slick, a basket or bucket could have been placed against the gutter, and material pushed into it, instead of scooped out of the depression. These gutters are to the left of the depression, suitable for right-handed use. It is interesting that what might have been a turtle effigy also had a practical use.

Of course, depressions on the tops of otherwise flat rocks could be natural.  However, these are noticeably concave  and are near camp sites. Their proximity to the shoreline would have made them useful for grinding acorns, since the acorn meal had to be soaked in water to remove the tannins before use.