=.21 = 
their waters to divide and redivide into many smaller streams, each 
of whose channels also finally becomes clogged so that néw ones are 
continually teing formed. Such channels are cut during and just af- 
ter warm hours of the day when floods of meltwater issue from the 
ice. The channels become filled and blocked with debris during the 
receding of the waters at night or in cold periods when currents are 
less swift. Thus these manifold streams form a braided pattern con= 
stantly shifting over the plain. ~In this ways first one- and then 
another part of the broad plain | is built upe * 
Since the meltwater is’ often fed from one fixed outlet in the 
glacier, or from between the ice edge and a nearby: mountain wall,the 
deposit gradually assumes a fan shape radiating from that soyrce. 
The constructional surface of this fan slopes away from the apex. and 
tends to be concave, for the coarser materials near the apex build, 
to a steeper angle than the fine material washed toward the outer 
edge. ay 5 : a aes 
One would expect that the largest boulders, cobbles, or pebbles 
rolled by the periodic flcods would be transported the shortest dis- 
tances. They would-come to rest before sand would settle, ‘The dis- 
tribution of material in the Mashpee pitted plain bears’ -out this 
principle. The average size of the particles composing the: -plain 
‘changes distinctly from that of well rounded gravel near the,epex to 
subangular sand at the outer margin. In the apex, rounded boulders 
6 to 24 inches in diameter are scattered over the surface. “One pit 
in this apex located near the Pocasset Road, 1000 feet north of its 
intersection with Jefferson Road (Plate II), shows 4+to6 feet of very 
coarse gravel overlying 3 feet of cross-bedded sand with thin gravel 
lenses; a trench in:the Military Reservation north of Snake Pond ex- 
hibits coarse gravel. Many shallow rdéad cuts show the general pres- 
ence of gravel in this part of the plain. ‘On the other hand, expo- 
sures in the wave-cut cliffs of the outer, seaward edge of the plain 
consist almost exclusively of sand. Pits excavated for sand used in 
surfacing roads and bogs are scattered along State highway, Route 28, 
and around each cranberry bog in this vicinity. ‘Very little-.coarse 
gravel is available in these pits. oe 
There are exceptions to this gradation in coarseness, however. 
Most notable is a pit operated by the Lawrence Co. and located just 
west of Sols Pond, 1 miles northwest of Falmouth Heights. Although 
this-locality is only a mile anda half from the southern edge of 
the plain, it shows a 6-foot layer: of extremely coarse gravel con- 
taining rounded boulders up to 18 inches in diameter. On the floor 
of the pit are a few boulders as much as 30 inches. long. Similer 
coarse gravel with rounded cobbles 8 inches in diameter occurs:in a 
nearby pit just- southwest of Teaticket Village. The eastward dip or 
slope of the layers and of the surface between pits in this vicinity 
suggests that this .unusually coarse material was deposited by melt- 
water that issued from the’ adjacent Buzzards Bay lobe while the Buz- 
zards ‘Bay moraine was under construction.‘ Apparently streams from 
that source built a small local fan on top of the more extensive .and 
older deposits of the Mashpee pitted plain at this place. 
