1881 .] 
199 
[Dodge. 
casional error in boring, from interruption by boulders, may here 
be ignored so far certainly as the general result is concerned. 
They seem to indicate two separate ledges or ridges of rock, one 
beneath Poplar and Milton Streets, the other extending from 
Lowell to half way between Leverett and Livingstone. Nearly 
all the soundings jfiace the ledge here at the foot of the hill below 
low water level. 
Poplar Street climbs the hill at its western angle, and the 
streets which cross it fall on either side. Brighton Street arches 
from 17.6 feet above base at Milton, to 18.6 at Poplar, and down 
to 18.2 at Allen. Kennard Avenue drops from 23.8 at Poplar, to 
20.6 at Allen. Spring Street from 23.5 at Allen, nearly reaches 
30 at Poplar, is 27.1 at Milton, and sinks to 21.9 at Leverett. 
These figures show a rise of 9.5 from one end of Milton Street 
to the other, a distance of 300 feet. Barton Street enters it 
about half way and is nearly on the 20-foot contour line. The 
region above the 25-foot level (which line crosses Poplar Street 
about half way from Kennard Avenue to Spring Street), includes 
the corner of Allen and Blossom, 26 feet, Leverett and Ashland, 
25.9 feet, Leverett and Causeway, 25.1. ' Ashland Street rises to 
31.7 at Chambers. Allen Street, 210 feet from Chambers, is 32.1. 
The contours of this hillock having been thus minutely stated, 
the data are at hand for forming a somewhat accurate idea of the 
underlying ledge from a few observations of its depth below the 
surface. Half way up the hillside, the ledge rises many feet above 
high water mark and approaches within four or five feet of the 
surface. Probably it furnished the material of which the under- 
pinnings of some of the older houses in the vicinity are built. In 
venturing this conjecture I do not forget that slate quarries were 
open in Somerville as early as 1685. 1 
The houses, numbers 67 and 33 Poplar Street, and those at the 
corner of Poplar and Spring, corner of Milton and Spring, and 
corner of Poplar Street and Kennard Avenue, are said to stand 
on the ledge rock. A sewer was laid in Poplar Street in 1848, 
1 For instance, on the north side of Somerville Avenue, between Central and Lowell 
and Lowell and Cedar Streets, and in the triangle enclosed by Broadway, Elm and Hol- 
land Streets. (Third Report of Boston Record Commissioners, pp. 196-9.) 
