158 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
is, in all probability, as previously shown, another bed of tillite. At 
Squantum Head a bed of tillite lies to the north of the sandstone. 
Under the tillite at Atlantic there occur contorted slate and sandstone 
layers with a predominance of slate. Just north of the tillite at Squan- 
tum Head contorted slate with a few sandstone layers appear. Now 
these beds are not duplicated at Squantum Head as they should be if 
doubled by folding. The order is what it should be if the beds were 
not doubled. It is true that such intercalated beds as these are very 
variable, and a bed in one outcrop might not correspond to a similar 
bed similarly placed in another outcrop, but the close correspondence 
of these beds at Atlantic and Squantum Head is more likely to mean 
a similar order of deposition, and the chances of coincidence are rather 
small. 
Slate layers, or “nests” are found, and also a few small fragments of 
slate. These layers or “nests” of slate may be found in the first few 
feet of tillite on both the north and the south sides of the Head. This 
deposition would be possible either in an advance, or retreat, or sta- 
tionary condition of the ice, so it might mean either top or bottom, and 
could not be limited to one or the other. If there is no duplication of 
beds by folding the thickness of the tillite is 600 feet, otherwise 300 
feet. 
There is some evidence of floating ice at Squantum Head, in 
boulders found in the slate. Plate 7 shows such a boulder. This 
one is of amygdaloidal melaphyre twenty-seven inches long and four- 
teen inches wide, and was found at the western extremity of Squantum 
Head near the contact of the tillite with the slate. 
Shearing has been very intense at Squantum Head, producing a 
cleavage with sharp dip to the northeast. 
Criteria found:— A, B, C, D, E, F, G, H, J, K, L, M, N, O. 
Locality 14._ Brighton. In a vacant lot west of 55 North Beacon 
Street, there is an outcrop which has been a puzzle to local geologists. 
The strike at this locality is E 8° S, and the dip 28° N. The matrix, 
which is less abundant than the included pebbles, varies from arena- 
ceous to argillaceous. There is stratification, and some assorting. 
The thickness exposed is about seventy-five feet. The pebbles are 
mostly rounded with a few angular and subangular examples. No 
striated pebbles have been found. Slate fragments abound. Mans- 
field (1906, p. 75) writes as follows in regard to this outcrop: —“ This 
ledge has given rise to some controversy because of the appearance of 
slate masses that resemble clastic material but are two feet or more 
in length and nearly a foot in width. It has been maintained on the 
