. 
"oe 22 - 
The leyering or bedding of the sand and gravel composing the 
plain resulted from alternate periods of flood :and slack water in 
the streams. Abrupt changes.in grain size distinguish adjacent lay- 
ers in all pitss;in places a coarse gravel bed. rests upon a fine sand 
bed, and vice versa.s The power of the currents which deposited thase 
beds was unusually variable. Even within a single bed of sand, cur- 
rent action has resulted’ in criss-cross patterns of. the fine layers 
lmown as cross~bedding. Groups of fine, light and dark, laminae of 
sand slope in many directions. © Such-cross—bedding was best exposed 
in 1939 ina pit along State highway, Route .22, at the head of Great 
Pond. In coarse gravel, the "scour and fill" nature of the deposit 
“is evident. Onthe southwest wall of the Lawrence Company pit re- 
ferred to above and in numerous gravel pits in-higher parts of the 
plain,. some of . the ease Havers orl broad SS ee like 
enseSe : ‘ eRe. OT Sie Setpttiee SRS arinitien| 
Saleataaat TTR 
All of the eiicker Henee whether they are extensive or not, are 
essentially, paraliel:.to the’ surface, of the.plain;.. none -is inclinsa 
steeply “forward ‘/in the direction of stream flow.. Such."foreset" 
structure would be indicative of a delta built by streams ina body 
of standing water, Lack of any such structure here, even in pits at 
the outermost edge of the exposed plain, indicates that this fan was 
built on land, and not to accord with any lake surface or sealevel. 
Eviderces of Buried Ice 
s 
The tremendous. natural pits in the plain .are most convincing 
evidence that this is glacial outwash. .These pits .occur chiefly in 
groups rear.Falmouth, Coonamessett, Massachusetts Natioral Guard Ri- 
fle Rangé, Forestdale, Farmersville, Newtown, the vicinity of Johns 
Pord, Waquoit, and Osterville. There is no system ‘or regularity to 
the grouping or tothe ‘positions of groups of pits in the plaine 
Hore than 30 pits exceed half a mile in length. They range in depth 
from 50 to 120 feet, and séveral. are enclosed completely by gravel 
walls to such depths. The most prominent examples are the depression 
which contains Snake Pond west of Forestdale and the hollows in the 
Massachusetts Guard Rifle Ranges near the -center of the Pocasset 
Mia 
quadrangle.* About 500 smaller pits: are shown as. depression contours 
on the rew EP oaoecaprse maps of the Geological Survey,and many others 
observed in the area under discussion are too small to show on maps 
of the scale used. The side slopes of the pits are inclined at an- 
gles ranging from 5 to) 202% Slopes around adjacent depression cen- 
ters’coalesce to form saddle-shiped ridgese The pits vary greatly 
in shapes; some are nearly circular, some elonzate ‘oval, and some 
quite irregular: Within an area of compound pits, the surface may 
resemble the hummocks and hollows of small "kame and kettle" depos- 
its so corion in the valleys throughout New England.’ 
These features -- the irregular grouping, the great depth, steep 
slopes, -and irrégular shape -- are prime characteristics of glacial 
kettle-holes, Such’ depressions were produced when masses of ice, 
seperated from the main’ .ice sheet, were surrounded and partially or 
completely covered by accumulating outwash gravel. Some years or 
