Groupings and Watersheds
Let me call attention to three groups of sites on the map.
- The largest group crosses the map from upper right to lower left
south into the Assabet River. This region is what geologists call the
- A second smaller group of sites appears along Hobbs Brook in
Lincoln, Lexington, and Weston. More sites, further down the watershed
(of the Charles River), are off the map to the south.
- A third group is located along brooks flowing into the Sudbury
More sites on this watershed are off the map to the south.
are very few sites between the Assabet and the Sudbury. Although more
exploration is certainly possible in this area, essentially no rock
piles have been found there.
discovery rate and the Learning
140 sites have been found. Here is a trend chart of number of sites
found per month.
At the beginning I located one or two new sites per month. Later,
the summer of 2004, after learning how to locate them, they were found
at a rate as high as three a week. The monthly information was not
pre-2000 or from June
2002 - June2003 so there are anomalies in the chart around Jul-98 and
In spite of this, the increase over time is clear and suggests a
The presence of the learning curve makes sense - I was learning how to
identify certain combinations of features on the topo maps before going
out to explore, and also was learning where to look once there, in the
Careful examination of the details of the map above
show how the sites are related to hills and water. In particular, the
majority of the sites are located where water comes out of the ground
begins to flow away downhill. Less frequently, sites are located on
shoulders of hills, especially ones with southern views over water.
Such conditions can be identified on a topo map even for areas that
have never been visited. To
illustrate this, here
is a random piece of topographic map, from west of here, with likely
places for rock piles circled. In the red circles, associated with
water coming out of the ground, smaller rock piles
built on support rocks are expected. In the blue circles, associated
with southern views over water, larger
piles built directly on the ground are expected.
This is a part of Leominster State Forest, where I had never been.
To test this statement, and it being a nice day, I went out and
explored in this area above the "C" in "Princeton" on the map. In the
fewer things are visible and it is hard to cover much distance but I
found at least two larger ground piles looking out southwest over
Paradise Pond (the lake under "I" in "Princeton"). These fit the
the blue circles. I also found a pair of piles near a
run-off gully, built on support rocks. These fit the expectations of
the red circles. Here are example pictures from Leominster State
The first picture is a typical "blue circle" pile and location. It
a marker pile with one central "marker" stone above a southwestern view
over a pond. The pile is on the ground, reasonably large, and
rectangular. The second picture is
a typical "red circle" pile and location. It shows a small pile with a
handful of cobbles on a support boulder. A few feet to the southeast is
a dip in the ground which provides a channel for run-off water. I did
not get to the exact
locations I had made predictions for but applying the principles did
lead to finding rock piles nearby. We might issue a challenge to
proponents: to find a rock pile site in the snow, a half an hour drive
away in an unfamiliar town - in less than an hour.
are probably not just from field clearing
One of the most interesting observation about the site distribution
is that rock pile sites are
concentrated in rocky upland locations which were orchards, pastures,
or swamp-land. In particular, where
field clearing never occurred.
We conclude that not only are
rock piles not just the result of field
clearing, in some cases they were probably even destroyed by
The actual site distribution is so much the opposite of what would
be expected based on the field clearing theory, it is hard to believe
(1) ever came in contact with more than one or two actual sites or, if
they did, that they have reported them accurately.
Examples from Concord are instructive. Concord, with its
fertile soil, probably had the most farming of any of these towns; yet
it has far
fewer rock piles than the less agricultural towns to
the north like Carlisle and Acton. The largest rock pile site in
Concord, on Annursnac Hill, occurs several hundred feet uphill
from lowlands which might have been plowed. Another significant
cluster of rock piles in Concord occurs along a ridge uphill from
Brook. Why would anyone carry rocks uphill to dispose of them? A third
in Concord, is located twenty yards into a swamp near one edge of
Estabrook Woods. A field could have been located nearby but why put
in the interior of the swamp rather than at its edge? There is no need
to look hard for answers. The field
clearing hypothesis is simply not consistent with most of these sites.
To be fair, a number of fields were cleared into rock piles. This is
seen at Great Brook Farm in Carlisle and at Weatherbee Conservation
Acton. At these places there are rock piles near the edges of fields.
Ironically, these sites have well defined characteristics which make
them easy to distinguish - with poorly made piles made of poorly sorted
glacial till all scattered around the edges of the plow-able land.
Before anyone ventures
opinions about the nature of rock piles in general, they should
acquaint themselves first-hand with known field clearing examples. How
differ from the sites in the uplands of Acton, Carlisle, Boxborough,
etc will then be more obvious.
As mentioned earlier, rock piles are most frequently found where hill
meets water. For example, a spring on a hillside is a very likely
location of a rock pile site; or a place where a hill descends into a
swamp. By their nature, such places are poor areas for farming. Rocky
hillsides and swamps were not plowed and often rock piles are found far
from any field which might have been cleared. This evidence is
perfectly straightforward. That it is not understood
by authorities in Massachusetts responsible for protecting sites is a
for further study
Once these sites are recognized as having a great deal of particular
structure, highly organized and consistent with landforms
where they occur, then it begins to seem likely they are Native
American and similar to mound sites found throughout the east and the
southeast (2). That this window into the ceremonial life of natives in
Massachusetts would still be available, in spite of farming and other
efforts to erase its presence, is good news for anyone interested in a
deeper understanding of the Indians of this region.