HOBBS.] 
ENGINEERING ENTERPRISES. 
11 
masses which project above the general level in order to mak< 
for business blocks and apartment houses. The majority of the ro< 
exposures described by Dana and other early observers are now no 
longer to be seen, and those still uncovered by blocks and pavements 
New St. 
Broad St. 
Fig. 1.— Rock surface beneath new Stock Exchange building, between New and Broad streets. 
Contour interval, 1 foot. 
will in a very few years have disappeared from view. That a like 
irregularity of surface characterizes the covered portions of the base- 
ment at the south end of the island is amply demonstrated by recent 
excavations (see, for example, fig\ 1). 
