Correspondence. 331 
says: — "Along the middle third of the sound the depth in the larger 
part is only 10 to 15^ fathoms. There is near the southern shore, how- 
ever, a depression of 20 to 25 fathoms. It ends with abruptness aVjout 
a mile and a half from the shore with a depth of I8I4, llf.^, 10, and 9 
fathoms." This abrupt termination is thirty miles short of the outlet 
to the sound, and is nearly opposite the Mattituck pond, which almost 
connects with Peconic bay. Profepsor Dana was quite confident that 
a relationship existed between them in glacial times. 
The present writer had arrived at the same conclusion by independ- 
ent investigation. Not only this, but on a visit to Mattituck during 
the summer of 1893, I could see, what perhaps had never occurred to 
Dana, a connection between the Mattituck depression and Canoe Place. 
At least it was very suggestive that this break in the terminal moraine 
should occur nearly in a line with the deep deprepsion referred to in 
the bed of the sound. The sviggestiou, of course, came naturally enough, 
as I had made a study of the same phenomenon on the west end of the 
island, where the bay depressions on the south side of the sound had 
been followed up through the moraines to the sea. All the connections 
between the Mattituck depression and Canoe Place are lost in the wa- 
ters of Peconic bay: but when it is understood that the same conditions 
prevailed here, during the Glacial period, as on the west epd of the 
island, the conclusion stated was easily arrived at. In fact, I had 
suggested this some years previously to my visit to Mattituck, and be- 
fore I had seen Prof. Dana's paper in regard to the sound depression. 
In a pamphlet on the formation of Long Island, published in 1884, I 
said: "Block Island sound, Gardiner's, Great and Little Peconic bays, 
were originally formed by subglacial streams, that came from the main- 
land, and are merely the counterpart of the depressions and basins 
on the west end of the island." I mention this because it was very 
gratifying to find my conjecture seemingly confirmed by subsequent 
investigation. 
The visit to Good Ground and Canoe Place was full of interest, not 
only on account of these geological problems, but thore was much to 
remind me of my native home across the ocean, e.specially in the Shin- 
necock hills, which rise beyond Canoe Place to an elevation of 140 feet. 
Some writer has said, "Looking at them, where no villa is in sight, one 
is forcibly reminded of the description of the moors of Lorna Doone." 
Eastport, L. I., N.Y. John Bkyson. 
A Granite Boulder near Pittsburgh, Pa. While geologizing 
around Carnegie, (formerly called Mansfield), in Allegheny Co., Penna., 
on August 30, this year, at a point just about 6 miles southwest of the 
confluence of the Allegheny and Monongahela rivers at Pittsburgh, 
namely about 500 feet northeast of Woodville station in Scott township 
on the P. R. R., in the bed of Scrubgrass run, I stumbled upon a very 
massive well-rounded erratic of red granite. 
This boulder was partially embedded in the gravel and mud of the 
stream, but is apparently about 2 feet 9 inches in diameter, and proba- 
