Correspondence. 65 
for about a hundred and twenty-five feet, and then the water would not 
be so good." This statement of Mr. Carman is all the more interesting 
at present as Mr. N. H. Darton of the U. S. Geological Survey, already 
referred to, seems confident that an unlimited supply of water can be 
found from those subterranean sources. 
The natural reservoir rises only to the level of the ocean, and reaches 
down to the clay bottom underlying the sand and gravel. These clay 
beds, however, as Mr. Lewis has shown, are not very uniform and are 
found at various depths. In the Woodhaven well, near Jamaica bay, a 
layer of bluish clay containing pebbles, was struck at the depth of 217 
feet, while according to Mr. Carman's statement a seam of blue clay 70 
feet in thickness was encountered in the Barnuin's island well at the 
depth of 55 feet. Very little water was found in these clay deposits. 
It is encouraging to find that the attention of the U. S. Geological 
Survey has been directed toward our little isle by the sea, for she seems 
to have been sadly neglected in the past. It is to be hoped that a thor- 
ough examination will be made, not only of the subterranean water 
sources at present in force, but of the old water ways that played such 
an important jjart not only in the formation of the Hempstead plains, 
but in the building up of the whole island. John Bryson. 
Eastjiort, Long Island, N. Y. 
The Nipissing-Mattawa River, the Outlet of the Nipissing 
Great Lakes.* When the waters of lakes Superior, Michigan, and 
Huron were making the Nipissing beach, their outlet was eastward over 
the Nipissing pass at North Bay, Ontario, to the Ottawa valley. This 
outlet river is called the Nipissing-Mattawa river and the three upper 
great lakes of that time are called the Nipissing great lakes. Mr. G. K. 
Gilbert visited North Bay in 1887, Prof. G. F. Wright in 1892, and the 
writer explored some of the ground at North Bay in 1893, and more, 
with a visit to Mattawa, in 1895. Last autumn a canoe trip of six days 
in fine weather was made from the head of Trout lake to Mattawa, thus 
covering the whole length of the Mattawa valley. 
The Nipi.ssing beach is well developed at North Bay at an altitude of 
about 700 feet above sea level. On the present col at North Bay the old 
outlet bed is somewhat over a mile wide, .30 to 35 feet deep at the max- 
imum and perhaps half that on the average. The average here, however, 
is not easy to get, for there was an archipelago on the south side, and 
not much is known as to the number and capacity of the old channels 
between the islands. The first swift water of the ancient outlet was at 
the foot or east end of Trout lake about 12 miles east of North Bay. 
The Nipissing beach though faint can be followed to the foot of Trout 
lake. 
The effects of the flowing current of the ancient outlet river are well 
marked at several points. The places of several ancient rapids and one 
cataract were found. The cataract was at the present Talon chute and 
the four most notable rapids were (1) below Turtle lake, (2) below a lake 
*.\bstract of paper read at Wasliiugton, December, 1896. 
