16 TRANSACTIONS OF THE [oct. 28, 
hundred yards north of the lighthouse, the upper stratified sands 
contain minute fragments of shells here also, showing the work 
of a transporting agency. 
In conclusion, therefore, we may infer that the stratified beds 
which mainly compose Nantucket are formed of the débris of 
older beds possibly mingled with the worked-over drift of the 
early Quaternary. We may also infer that Prof. Verrill’s de- 
ductions from the characteristics of the fossils enumerated, al- 
though they may be true of the original deposits, cannot be 
accepted as holding good for the beds as they occur at Sankaty 
Head. 
NOTES ON THE GEOLOGY OF BLOCK ISLAND. 
By Freperick J. H. MERRILL. 
This island, which is about 15 miles northeast of Montauk 
Point,is the eastward continuation of the deposits which occur 
on Long Island and forms a link in the broken chain of hills 
which marks the former southern extension of the continental 
glacier along the coast of New England. It is nine miles long 
and five miles broad in the widest part, and is noticeable from a 
distance on account of its high elevation, a large portion of the 
island being about 125 feet above the sea, Beacon Hill, the 
highest point, having an altitude of 210 feet. As at Gardiner’s 
I., and elsewhere, the stratified beds are upheaved in parallel 
folds which trend from east to west and the general surface con- 
forms to these elevations, but the undulating surface of Mon- 
tauk Point is here presented on a larger scale, the minor inequali- 
ties of the surface bearing no visible relation to the disturbance 
of the underlying strata. 
As shown by the map, the island is divided into two principal 
areas of elevation by Great or Salt Pond, which contains about 
1000 acres and is somewhat more than seventy feet deep. This 
body of water was formerly a bay connected with the ocean on 
the northwest, but at present it is separated from the sea on 
either side by low and narrow necks of sand, beach and salt 
marsh. The northern area of elevation presents on the east an 
extensive section in the bluffs near Clay Head, which extend for 
a mile and one-half from north to south and have a maximum 
altitude of about one hundred feet. The formation here con- 
sists of stratified sand, gravel and dark lignitic clay raised up 
in anticlinals of 15° to 20° slope and overlaid bya thin stratum 
of surface drift or till. The lignitic clay which occurs through- 
