SAYLES: THE SQUANTUM TILLITE. 145 
The lower part of the till usually has a finer matrix and more 
striated pebbles than the upper part. 
The materials in till showing that when deposited there was no 
evidence of weathering or decomposition. 
Materials in till usually composed of more local than foreign rocks. 
Near the top of till, intercalated stratified beds may be found. 
Included “nests”’ and layers often contorted. 
a 
DESCRIPTION OF LOCALITIES. 
In descriptions of conglomerates the words “pebbles” and “boul- 
ders”’ are used, as a rule, very indefinitely. In this paper I propose 
to use the word pebble for sediment from % of an inch up to 5 inches; 
the word boulderet for rock fragments from about 6 inches up to | foot 
in diameter; the word boulder for rock fragments over 1 foot in diame- 
ter. 
Locality 1. Hyde Park. At Hyde Park the sandstone and conglom- 
erate beds just under the tillite, strike N 30° E, and dip 70°S. About 
100 feet of the tillite is exposed. The matrix of the tillite is very fine, 
originally of clay. So far as I have observed them the pebbles, 
boulderets, and boulders are of granite, felsite, and quartzite, but 
other varieties may be found later. The shapes of the rock fragments 
indicate glaciation; angular and subangular for the most part, but 
here and there rounded. Dr. La Forge found a well-striated pebble 
embedded in the matrix, in the presence of Dr. Ellsworth Huntington 
and the writer on July 11th, 1910. This pebble is shown in Plate 2. 
I have since found two others from this outcrop. There is a large 
boulder of granite in the matrix within a few feet of the place where 
Dr. La Forge found his striated pebble, beyond the fence back of the 
Becker Milling Machinery Company’s storehouse. This boulder 
measures somewhat over three feet in diameter, and is angular. This 
spot is very near the bottom of the tillite, where it would be most 
natural to find striated and well-glaciated pebbles. There are no 
intercalated beds visible in the tillite of this outcrop, and absolutely 
no stratification of any kind. No fragments of slate have been found, 
and this is an important fact to be dwelt upon later. I have found 
no melaphyre fragments or pebbles. Shearing is intense. See 
Plate 1. 
Below the tillite there are some transition-beds of conglomerate and 
sandstone about 100 feet thick. 
Criteria found (see page 144): — A, B, C, D, E, F, G, H, J, K, L, M. 
