1881 .] 
207 
[Dodge. 
The slate under the puddingstone west of Grove Street in 
Watertown, between Belmont and Mt. Auburn Streets, has been 
lately more extensively exposed to view. A new road on the north 
side of Mt. Auburn Street near Walnut Street has broken into this 
ledge, which extends, mostly beneath the surface, from Newton 
Corner nearly to the Cambridge line. This better opportunity for 
observation than was afforded by the small natural outcrop there, 
shows the slate to contain occasional pebbles. The dip is to the 
northward, about 55°. A small six-inch dike runs nearly east and 
west. An artesian well on Spring Street, Watertown, passed about 
350 feet of sandstone before reaching slate. Borings by the city 
engineers of Cambridge near the outlet of Fresh Pond have 
reached slate at a depth of 148 feet. 
South of the Poxbury Puddingstone. At Savin Hill, occasional 
beds of sandstone may be found with the conglomerate, but there 
is no conspicuous change to the finer grained strata upon the slope 
north of Grampian way. Fragments of slate are found in the 
gravel close to the puddingstone, and half a mile south-south- 
west, the drift is full of them. On the southern side of Meeting- 
House Hill the puddingstone passes into sandstone with a south- 
erly dip on East Street. There is probably much slate beneath 
the surface in the next half mile southward. South of Charles 
Street, east of Field’s Corner station (Ashmont Branch), slate 
passes southward into puddingstone which extends along Free- 
man Street ; and on the same line of strike, sandstone and con- 
glomerate beds north of Dickens Street, in the line of Duncan 
Street, have the same southerly dip. 
The statement in my paper of 1875, that the ledges south of 
Mt. Bowdoin station show change of puddingstone to slate (Pro- 
ceedings, B. S. N. H., Vol. XVII, p. 408), I regard as erroneous. 
After having reexamined the ledges at that place, I do not know 
of any exposure of such a passage. I shall be glad if any one 
who has made a similar statement, will point out some locality. 
Along the south side of Canterbury Street, west of Blue Hill 
Avenue, there are sandy beds with strike about eight degrees north 
of East and south of West. Very coarse conglomerate forms a 
hill two hundred yards south-west of this exposure. There is 
also puddingstone east of Morton Street. It passes southward 
