Satles, — The Squantum Tillite. 



PLATE 2. 



Striated pebble from Hyde Park. 



Shows striae in numerous directions. On the right is the typical concave 

 fracture due to pressure of ice. A crack due to shearing is shown above, dip- 

 ping at an angle of about 60° towards the right. Another crack crosses this one 

 and dips in the opposite direction. The latter was made in extracting the 

 pebble from the matrix. There is also a fresh fracture on the upper left. 

 Note the wide type of striae. The pebble is quartzite. Found in tillite matrix 

 by Dr. Laurence La Forge, in the presence of Dr. Ellsworth Huntington and 

 the writer, 11 July, 1910. A trifle under natural size. 



