Field clearing and wall enclosed rock piles

Several weeks ago we had a brief discussion of rock piles that were enclosed in a retaining wall. For classic examples see here and here. I went back to take a look at the latter site and came away with the disappointing conclusion that this is, in fact, from field clearing. FFC and I agreed on that as we walked around the site. Believe me, I would much rather think these are ceremonial, I just cannot reconcile it with observations.

To be as clear as possible, I am not talking about piles with retaining walls but, more specifically, piles enclosed within a stone wall that does not retain the pile completely. In the examples above, note how the fill of the rock pile does not go all the way to the top of the wall that encloses the pile. I have been puzzling over that for a while - one reason to go back and have a look at that site in Carlisle. Also, I went back to look at Ted Hendrickson's pictures from CT that stimulated the discussion (see here) and I cannot make up my mind about those examples.

At any rate, here at the Carlisle site I came away convinced these were from field clearing for several rather basic reasons:

1. The site is at the bottom of a slope that was cleared of rocks. Overall this part of Carlisle is very rocky, so clearing that slope was an immense effort and the debris from it must have ended up here in these walls and pile.
2. There were many examples of smaller rocks dumped into piles separately from larger rocks, following the expectation that the fields were cleared in the order of: larger rocks first, then smaller ones
3. One sees "angle of repose" at the center of the rock pile
4. All of the stone walls here (at the north end of Two Rod Road coming up from Concord through Estabrook Woods) have occasional sections with an extra side wall and fill between the primary and side walls.
   

Number (4) is most telling because this kind of debris filled wall is a pretty standard stone wall design and it is perfectly believable as a field clearing mechanism. To deny that such walls were from field clearing is almost nonsensical. And here in Carlisle such walls run right up to and include the stone piles:But the observation that the pile does not actually fill the enclosing wall is puzzling. And I was trying to come up with a scenario for it.

The scenario:
A farmer starts clearing a field and dumps rocks into a pile. As the pile grows it starts to spill out sideways, leaving a mound towards the center which is at the "angle of repose" for dumped rocks. Later the pile grows more and the farmer, to prevent further sideways spill, puts a quick wall around the pile and continues filling it. [Jim P commented that these walls are made with care. I don't think so. We have on record that a hard days work for one man could produce something like a 1/4 mile of stone wall (this was in old records of work done on the island of Naushon - sorry no reference, and my recall may be faulty). So building a retaining wall should not be considered a particularly time consuming task.] Once the wall is in place, the farmer goes on filling the enclosure, sometimes up to the top of the wall and sometimes not.

Let's look at a particular example from this point of view:This was on slightly higher ground but we noticed some rock outcrop or larger boulders underneath. So the thought is that this was wasted land anyway. You can see different sized rocks dumped in there. You can see spillage coming out the sides. You can see a plausible scenario for this being just what it should look like: a field clearing pile with a slight effort to keep it away from spilling into surrounding field.

As FFC and I left the area, going back north to where the car was parked at the Malcolm Meadow Conservation Land parking lot, we took another look at the walls along the sides of Two Rod Road. There was not question that they were in the exact same style as the rock piles. No reason at all to suppose an alternate history for the piles. Here is a last look at the largest pile, built into a stone wall:
This is a disappointment but probably worth trying to be straight about. I remain unsure about the examples from CT, and certainly not all piles with retaining walls need to be dismissed. But look at the combination of factors, including nearby fields, including whether the wall actually retains and is filled to the top, including whether the sizes of rocks are uniform or, if mixed, segregated into homogeneous sized rock sub-piles.