Dodge.] 
206 
[May 18, 
body of the rock and caused by the greater abundance of the 
quartz-, epidote-, or calcite-filled cavities. Whether the portions 
which have this effect when seen in section were in part formed 
independently of the surrounding rock under different conditions, 
or whether they differ only in being spots of local concentration of 
forces of irregularly diffused operation, is worth considering. The 
fact may conveniently be observed south-east of the corner of 
Harvard and North Beacon Streets, at the east side of Allston 
Street, south of Allston Square Street, the west side of Allston 
Street opposite Allston Square Street, or the east side of Foster 
Street south of Mt. Yernon Street. 
The most southerly and perhaps the largest mass of amygdaloid 
is that between Chestnut Hill Avenue and Foster Street south of 
Mt. Yernon Street. This rises to the height of 160 feet. 
On the north side of Washington Street, opposite Lake Street, 
the gandstones are evenly bedded, with a dip of about 25°-35°. N. 
The strike is from N. 80° E.-S. 80° W., to E.~W. About 55 feet 
of strata are exposed in the cliff on the south side of the hill, the 
upper portion being coarse puddingstone, and the whole is capped 
with amygdaloid which on other sides of the hill may be exam- 
ined in walls 20 or 25 feet high, where the rock has been worked. 
Westward the junction descends obliquely across the southern 
face of the hill, reaching its foot at the western end. 
The rock which occupies an area between Homer and Fuller 
Streets, and the puddingstone south of the Boston and Albany 
Railroad in Newton, extending from Murray Street nearly to 
Maple Street, may be examined at several points on Yalentine 
Street where it was blasted at the laying out of the street four or 
five years ago. There is a resemblance between this rock and one 
of the varieties west of Mattapan. The mass of the rock is dull 
green with occasional pale yellow and some dark red spots and is 
occasionally porphyritic with crystals never of great size. There 
is much quartz in irregular veins, and some asbestus. The rock is 
probably older than the stratified rocks which surround it 
closely ; from a few hasty observations I think that the similar 
rock near Mattapan is represented among the pebbles in the con- 
glomerate at that place. 
