220 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
of the village now known as Pondville. A few years later (1894) 
Woodworth described a fossiliferous section in the railroad cutting 
three-quarters of a mile’ north of the station at Canton Junction. 
The section at this locality had previously been noted by Dodge in 
the paper already cited (Dodge, a, p. 414). In his report on the 
Narragansett Basin (1899) Woodworth gives some account of the 
Norfolk Basin rocks and speaks more particularly of the section at 
Pondville. The latest and most extensive account of the rocks of 
this basin is found in the paper by Crosby (1900) entitled The Blue 
Hills Complex. To this paper the writer is indebted for much of 
the data used in the present discussion. 
Form of the Basin. The Norfolk Basin extends northeast from 
Sheldonville, Massachusetts, where it joins the Narragansett Basin 
through a narrow pass (Franklin VI, LM 18-20), about twenty miles 
to Great Pond in Braintree, where it apparently ends. ‘The general 
form of the basin, as shown in Figure 8 (p. 230) is a relatively nar- 
row trough decreasing in width toward the northeast. It is approx- 
imately two miles wide where it is crossed by the Providence Division 
of the New York, New Haven, and Hartford Railroad; in the longi- 
tude of Ponkapoag Pond it is a mile and a half in width and eastward 
it narrows rapidly so that in the vicinity of Great Pond it is certainly 
not more than half a mile wide (Crosby, n, p. 467). 
The Northern Boundary. The eastern portion of the basin imme- 
diately south of the Blue Hill Range is the only region where the 
northern boundary of the sediments can be located with any degree 
of precision. Elsewhere the drift cover is so complete as to render 
its position uncertain. The marginal rocks in the vicinity of the 
Blue Hills consist of very coarse accumulations styled by Crosby 
the “giant conglomerate,” composed of boulders one or two feet in 
diameter and sometimes even three or four feet in diameter, usually 
well rounded or water worn (ibid., p. 471). Fine exposures of the 
rock occur in situ on the steep cliff-like slope 600 to 1,000 feet west 
of the junction of Randolph Avenue and High Street (Dedham VII, 
D 18) and at the “Streamside Ledge” half a mile east of the same 
point. At each of these localities the main feature of the rock is the 
abundant occurrence of boulders composed of the Blue Hills porphyry; 
other types of pebbles occur but no pebbles of felsite flows or of the 
normal granite (ibid., p. 471-473). Dips are not well shown by the 
conglomerate but occasional sandy or shaly bands indicate a southerly 
direction varying from 70° to 90° (ibid., p. 468). From alteration 
in the porphyry and from pebbles in the adjacent conglomerate 
