rave been filled with strean gravel. to the level.of..the channel 
FIGOrs As this is not true, it is inferred that the. blocks of ice 
rerained not only until the plain was built but also until the fur- 
rows hac been cut ; 
Moreover, some of the buried ice was present when .the adjacent 
men ines Were supsrimposed upon the edges of the plain... Thin active 
ice moved forward over this gravel and deposited till without de- 
stroy ing the ‘layers of gravel beneath. Masses of decaying ice caught 
eer the first outwash gravel. remained until the active ice over- 
ode them, inasmuch as certain large kettle-holes already described 
(Page 23) extend from the exposed surface of the fan into the mo- 
raine-covered area. The ice finally melted away afttar both the grav- 
el of the fan and the till of the moraine had been deposited, 
f£, then, ice lasted many tens or a few hundreds of years while 
tre plain-was being: built, afew hundreds. of years while, ventifacts 
rere being cut, ‘and perhaps many score years while the furrows were 
being eroded and moraines were being superimposed, it may be stated 
with confidence that this buried ice persisted at least for several 
centuries. It is probable that vegetation had gained a foothold on 
Cape Cod long before the last buried ice had melted or evaporated. 
~ 
‘The final event that bisector the cere aspect of the Mashpee 
ted plain was the drowning by the sea, At.no time .since comple- 
ion of the plain has sealevel’been higher:on: this: portion of -Cape 
qd than at is today, for no sandbars were. found. above the modem 
ore line. These would certainly: be -_present had wave action once 
been higher on such a-sandy shore. Moreover, none of the kettle- 
holes at the lower edge of the plain-are filled by wave wash. On 
the other hand, submerged stumps of cedar trees have been dredged 
from below low tide- level at Witchmere Harbor in Farwichport, 15 
miles east of this pitted plain’ (2, Page 25),and at Centerville (4a) 
near its eastern edge. The lower end of each furrow is clearly 
rowned,and no process of shore erosion orconstruction could produce 
such a deeply indented shoreline. Sometime within the last 10,000 
years the sea rose toits: present’ stand with respect to all this sec- 
tion of Cape Cod,and andes were built acrass many of the bays and 
estuaries. : 
Ground water, ' which ecireces the sand and gravel under the 
plain, rises to a height somewhat above sealevel. In the higher 
northwest portion of the fan only the pits .80 or more feet deep are 
low enough to contain open lakes... Along the lower southeast edge 
even some of the shallow pits 10 to 20 feet deep contain water. 
These indicate the uppermost level of ground water, because the top 
‘of the saturated zone in gravel can stand but ‘little higher or. lower 
c the surface of open lakes -in depressions. For never-failing 
supply; all wells must be sunk to this level. Four miles from 
apex o@ the fan this water table is about 60 feet above sealevel. 
drops systematically southward urniti1,10.to 12 miles from the apex 
the fan, it coincides with sealevel. +: It slopes more gently than 
a) 
h 
aan 
