176 
erate and melaphyr in the area between Hull Street and Straits 
Pond are due to faults, as stated on page 75. The more prob- 
able view is that expressed on the map, viz., that the alternate 
contacts are faults. The conglomerate of Round Hill and Con- 
glomerate Plateau, with a gentle southerly dip, is overlain by 
the second melaphyr; and the outerops of these two beds are 
repeated several times by east-west displacements downthrowing 
to the north. 
Recent observations have thrown additional light upon the 
relations of the dikes of the central belt in the vicinity of Hull 
Street ; and nearly all the dikes in the section on the railroad сап 
now be traced across Conglomerate Plateau. Nos. 25 and 27 are 
clearly the same dike; and this can be traced now, as shown on 
the map, to the intersection of Hull Street and Atlantic Avenue. 
Just west of Hull Street it appears to cross the course of 
29; and what appears to be a branch from the latter quite clearly 
cuts 25 on the north side of Hull Street, and then runs parallel 
with it. No. 81 also branches near Hull Street; but there 
seems to be no way of definitely deciding whether the dike 
which ultimately reaches the shore of Strait’s pond is 29 or 31. 
No. 24, on East Porphyrite Hill, is cl 'arly а continuation of 38, 
on Granite Plateau ; and there is a clear path for it across Cliff 
Plateau, although it does not appear to be actually exposed. 
l'or the elevations of some of the drumlins in Cohasset I am 
indebted to Mr. H. W. Nichols, a student in the Geological 
Department of the Massachusetts Institute of Technology ; and 
for many of the names on the maps I am under obligations to 
Col. E. T. Bouvé. He has prepared a very interesting chap- 
ter on the ancient land-marks of Hingham and Cohasset for the 
forthcoming history of Hingham, and has kindly permitted 
me to use the proof-sheets. 
I also gladly embrace the opportunity which this supplement 
affords to acknowledge the important aid in the prosecution of 
this work which I have received during the past year from Mr. 
Thomas A. Watson. He has not only made possible a great 
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