MUSEUM OF COMPARATIVE ZOOLOGY, 20 
bear smooth surfaces, and the beds of limestone which outcrop in the 
valleys are rounded and water-worn, none of these rocks exhibit well- 
marked striw. This peculiarity is probably due to the great amount of 
decomposition which the surface of these rocks has undergone. 
In the case of the mica schists and argillites, the slight amount of 
decomposition which they have suffered, and the coarseness of the striations 
which they have received, have prevented the obliteration of the markings. 
Though there is a great difference in direotion between certain widely 
separated sets of striæ, yet it is generally true that the strie situated 
upon the same N. E. and S. W. line, have, if not separated by a great 
distance, nearly the same direotion. 
4, SUPERFICIAL DEPOSITS UNDERLYING THE TRAINS. 
The superficial deposits of the region consist of unstratified gravels 
made up of wacer-worn fragments of all sizes, and composed of limestone, 
quartz, quartzite, mica schist, chloritie schist, and chloritio sandstone. In 
a cut on the Boston and Albany Railroad, three quarters of a mile N. E. 
of Richmond Station, are completely rounded and polished boulders, 
some of which have a length of four or five feet. They are composed of 
limestone and of chloritic schist, and a few exhibit well-marked parallel 
Strim. The thickness of the drift deposits diminishes from the base 
towards the crest upon each of the three ranges in the region, the sum- 
mits or crests being in nearly all cases free from this formation, though 
in several instances the bed-rock is concealed by a scanty soil bearing a 
thick vegetable growth. 
The following table gives the thicknesses of the drift deposits in vari- 
ous localities. 
Table of Thicknesses of the Drift. 
(1.) Channel of brook between’ North and South “Families” of Ca- 
ARA DM SS Sn eco ی وه ما‎ A Teese T» 20 feet. 
(2.) Channel of same brook in ravine between Flat Rock and Merri- 
A CUE ts AO NOT OM E OD CE Gita dul ted rud 25 “ 
(3.) Channel of brook near head of ravine hetween Merriman’s and 
DIO noni o ds Sie 
(4.) Channel of brook } m. east of summit of Perry’s Peak.............. er 
(5.) Channel of brook $ m. north of Haskell’s, in the Haskell Valley (at 
sats PME NO PLUR ARRA eR IRA TRU $85‏ تا 
Channel of same brook # m. nearly south of Haskell’s............... 14%‏ ).6( 
Channel of brook $ m. S. S. E. of summit of Perry’s Peak... 3 “‏ ).7( 
(8.) Channel of same brook 4 m. N. N. W. of Miss Pearson's........... $t 
