Page 628 - calmining1890

592 EEPORT OF THE STATE MINERALOGIST.

This stratum contained a good supply of water, which rose to the t
of the well. Wells bored in the marsh land are said to be frequem
much affected by the rise and fall of the tide.
Westward from Redwood City, the area of flowing wells, as far as i
been developed, appears to be confined to the marsh land borderi
the bay, to the bay itself, and a few exceptions of instances towards t
northern extremity of the county. A well was bored in Wellesly Pai
about one and a half miles west of Redwood, to a depth of about eigh
feet, before a supply of water was obtained. After passing through i
teen feet of clayey soil, a stratum of gravelly clay was penetrated, whi
was sixty feet in thickness; beneath the clay, loose bowlders were e
countered. This stratum yielded a supply of water, but gave mut
trouble in boring.
The town of San Mateo obtains its water supply from the Spring Valli
Waterworks and from surface wells.
The wells, which have been dug to the depth of twenty-five or thir\
feet around the town, yield an abundant supply of surface water. Tl
soil is from ten to twenty feet thick, beneath which is a water-bearh
gravel; this the wells usually penetrate for some fifteen or twenty fee
South of San Mateo Creek the land is a little more elevated, and tl!
wells average perhaps ten feet deeper.
West of the town of San Mateo the wells are also deeper; on the Pa
rott Ranch, about one mile from the foothills, a well was bored to
depth of three hundred feet. The boring was nearly all the way in roc:
About twenty-five years ago a well was sunk near the railway dep<
to a depth of eighty feet; twenty-five feet of soil were passed through, an
the gravel penetrated for about sixty feet. The water rose to withi
thirty feet of the surface, and practically an inexhaustible supply coul
be obtained by pumping.
At the Howard Ranch, which is reclaimed marsh land, about a mii
southeast of San Mateo, thirty wells were bored, varying from twent}
five to one hundred and twenty-five feet deep, and one which was thre
hundred and forty feet deep. They flowed fifty thousand gallons ever
twenty-four hours during a dry season, and during a wet season upward
of one hundred thousand gallons.
These wells are situated within an area of a few square miles, ano
within a distance of two miles from the edge of the bay, yet there is q
lack of uniformity in the volume of water they yield that is somewha
remarkable. Some of them are greatly affected by the tide, and other
much less so. Thus, some of the wells rise from ten to fourteen inche
above the ground at high tide, and at low tide they cease to flow. Th
well nearest the bay, which is about five hundred feet from high-wate
mark, is only forty-seven feet deep. It flows ten inches above tin!
ground at low tide and twenty inches at high; while one which is closf
to. the San Mateo Creek, and only eight hundred feet distant, is on<
hundred and twenty-seven feet deep, but it only flows six inches abovi
the ground at high tide, and at low tide it ceases to flow. The on<
farthest west is ninety-six feet deep, but it does not come within thre<
feet of the surface. The total cost of boring and casing these wells
was about $3,000.
From a comparison of the various borings, the following is an idea,
sketch of the strata passed through.
Vertical sketch of strata on Howard Ranch: