BERKEY, GEOLOGY OF SOUTHERN MANHATTAN ISLAND 263 
roborate the judgment of their character and relationship. I have been 
assisted in every way by the engineers in charge in finding and handling 
these materials. 
The East River bridges are known as 
No. 1, or the “Brooklyn Bridge.” 
“ 2, “ “ “Williamsburg Bridge” or the “New East River Bridge.” 
“ 3, “ “ “Manhattan Bridge” (now being constructed). 
“ 4, “ “ “Blackwell’s Island Bridge” or “Queensboro Bridge.” 
“ 5, (A projected one on the northeast side and immediately ad¬ 
jacent to Brooklyn Bridge). 
Bridge No. 1, .“Brooklyn Bridge” 
Datum is M. H. W., 1.93 ft. above mean sea level at Sandy Hook. No 
cores seen. 
(See Bridge No. 5, which gives data for the same locality on both the 
Brooklyn and New York sides.) 
Bridge No. 2, “Williamsburg Bridge” or “New East River Bridge” 
Materials from drill borings at both piers are completely labeled and 
housed in the office in Brooklyn, 84 Broadway. They are one inch diamond 
drill cores and are lettered A, B, C, etc., on each side of the river. The 
datum is M. H. W. and is 2.67' above mean sea level at Sandy Hook 
(U. S. datum). 
a) Brooklyn Tower foundation. 
Serial No. 
Original 
mark 
Location 
Depth 
to rock 
M. H. W. 
To Rock 
U. S. 
datum 
Rock 
penetra¬ 
tion 
Form¬ 
ation 
Variety and remarks 
43 
A 
N. pier E. side 
-105.0' 
-102.33' 
7.04' 
Ford. 
Granitic gneiss rather 
flat, 6' core. 
44 
B 
Center line of 
bridge E. side 
-80.4' 
-77.73' 
16.73' 
“ 
Granitic gneiss, 9' core, 
15° dip. 
45 
C 
N. pier W. side 
-96.7' 
-93.03' 
16.0' 
Black and white banded 
granitic gneiss, 3' core. 
46 
D 
Center line of 
bridge W. side 
-85.0' 
-82.33' 
20.24' 
Quart zose gneiss, some 
hornblende type, 17' core, 
10°-25° many pieces. 
47 
E 
S. pier E. side 
-S0.0' 
-77.33' 
10.35' 
Gray banded granitic 
gneiss, 6' core, steep dip. 
48 
F 
50' S. of S. pier 
-76.0' 
-73.33' 
14.0' 
Striped gray granitic 
gneiss, 8' core, 50° dip. 
