QUATERNARY DIVISION. 
137 
with veins of quartz and granite; two hundred feet of the upper part of the bore is a three 
inch hole, and the remainder two and a half inch. The water obtained from this well was 
at first tolerably good, and promised to be very serviceable, but since has very much deterio¬ 
rated, and is now said to be even more saline than that of the neighboring river. 
“ On the west side of the island, at Washington market, which is on the west side of 
Washington-street, between Fulton and Vesey-streets, a shaft was sunk ten feet through arti¬ 
ficial earth ; fifty feet through river mud, containing decayed vegetable matter, sands, clays, 
etc., in thin alternating strata ; ten feet of sands and gravel, when the rock was reached at 
seventy feet from the surface. 
“ Again, at the corner of Grand and Wooster-streets, a shaft was sunk forty feet through 
artificial earth; then twenty feet of mud, clays, and sands highly charged with decaying 
vegetable matter ; then six feet of fine blue clay ; and lastly, six feet more of coarse sand and 
gravel, when good water being obtained, the borings were discontinued at the depth of seventy- 
two feet from the surface. The depth was considered as at, or at least as very near, the sur¬ 
face of the rock, from the fact that in almost all cases where the rock was reached at great 
depths through similar strata, it was found covered with a bed of gravel or sands, like that 
above mentioned. 
“ In College place, directly north of Columbia College, which is on more elevated ground 
than the market, the rock was reached at the depth of eighty feet, through twenty feet of 
diluvium and sixty feet of stratified sand and gravel alternating. If we follow the high range 
of grounds in a longitudinal direction, as in the neighborhood of Broadway, though we have 
fewer data from which to judge, yet it is believed that the rock here approaches nearer the 
surface than in the places above mentioned. This is inferred from the fact that the direction 
of Broadway corresponds with that of the strike of the strata, and is generally more elevated 
than the grounds on either side of it; and the contour of the rock follows, it is believed, that 
of the loose earth which covers it. 
“ At the old rock well near Trinity church, the shaft was sunk twenty-six feet through 
diluvial gravel and sands, when the rock was reached, though not penetrated, and good and 
permanent springs of water obtained. At the City Hall, the shaft was sunk ninety feet to the 
rock, but is in the district of the Collect (see vertical section, PL 3, fig. 1). The celebrated 
well, corner of Bleecker-street and Broadway, is four hundred and forty-eight feet deep ; forty- 
two feet through stratified sands and gravel, and four hundred and six feet in solid rock, 
having the usual character of the gneiss of the island. The bore of the shaft is seven inches 
diameter, and yields one hundred and twenty thousand gallons in twenty-four hours, ac¬ 
cording to the statement of Mr. D. senior, who made the borings, and who also states that 
the water rose within thirty feet of the surface, 
“ The shaft of the city reservoir, in Thirteenth-street, a few feet east of Broadway, is one 
hundred and thirteen feet deep and seventeen in diameter, with two adits at bottom; one 
seventy-five, the other one hundred feet long. The rock was reached at about twenty feet. 
“ In the same street, a few rods west of Broadway, the rock was reached at the depth of 
about three feet, approaching in one place very near the level of grading. At Sixteenth- 
Geol. 1st Dist. 18 
