1879.] Hillocks or Mound-Formations of San Diego, Cal. 565- 
height. From Nausett Lights to High Head much of the cape, 
as it originally was, has been demolished, and the process is still 
going forward; but the sea restores a part of what it takes, form- 
ing this curved bank of sand, five miles long and one to three 
miles wide, which encloses the deep and commodious harbor of 
Provincetown. The section here, to a depth of one hundred and 
eighty-two feet, was shown by a boring made some twenty years 
ago at the end of Central wharf. Sand extended from low tide 
line for thirty-five feet, below which interstratified sand and fine 
gravel continued to one hundred and seventy feet, where the first 
clay was encountered. This was dark-colored and very compact, 
extending twelve feet, at which depth it was not penetrated. 
Shells of Scapharca transversa, Ostrea virginiana (at one hundred 
and twenty feet), Lunatia heros and others were found to the 
depth of at least one hundred and forty feet. Successive genera- 
tions of these inhabitants of the sea have been buried during this 
accumulation of its detritus, and at the same time its waters have 
probably been gradually rising upon the land. 
The height of the principal hills of this town, as determined by 
Major Graham of the Coast Survey, are as follows: Mt. Ararat, 
one hundred feet above mean low tide; Mt. Gilboa, one hun- 
dred and six; Oak Head, one hundred and four; Miller’s hill, 
eighty-nine; High Pole hiil, one hundred; Telegraph hill, ninety- 
eight; Creek hill, eighty-four. These are dunes on the harbor 
side which have mostly become covered with bushes and trees. 
Others of nearly equal height, occupying the side next to the 
ocean, are drifted by every passing wind, allowing no foothold to 
vegetation ; and clouds of sand, seen at the Highland Light, are 
lifted from this tract by gales to the height of three or four hun- 
dred feet. 
—_——O.—— 
THE HILLOCKS OR MOUND-FORMATIONS OF SAN 
DIEGO, CALIFORNIA! 
BY G. W. BARNES, M.D. 
aoe surface geology of many sections of the Pacific slope is 
characterized by innumerable hillocks or small mound-like 
formations, either sparsely distributed or occupying quite densely 
areas of considerable extent. These formations, variable in size 
_ Read before the San Diego Society of Natural History, April 5, 1879. 
