22 POPULAR OFFICIAL GUIDE. 
In three of the four principal valleys of the Park, bogs 
have been converted into ponds, and in the largest and deep- 
est of all he Bronx Lake and Lake Agassiz. The bed-rock 
underlying or cropping out in the Park exhibits pink gran- 
ite, gray granite, rotten gneiss, and quartz in bewildering 
variety. Occasionally in trench-digging a ledge is encoun- 
tered which yields good building-stone for rough work, but 
usually our rock is so full of mica as to be worthless. 
The water-levels in the various portions of the Park are 
as follows: 
Above Sea Level. 
Surface of Bronx Lake................ 20.40 feet 
Surface of Lake Agassiz.............. 31.70 ‘ 
Surface of Cope Lake and Duck Ponds.. 47.00 ‘‘ 
Surface of Wild-Fowl Pond............ 65.00 ‘S 
Surface of Beaver Pond............... 44.00 ‘ 
The floor levels of some of the important buildings are as 
follows: 
Above Sea Level. 
Of the Antelope House................--4- 88 feet 
Of the Reptile House.................... 78 SS 
Otsthe Woion- Houses 3 vin aca see 64‘ 
Of the Aquatic-Bird House.............. ott. 
Soil.—The soil varies from rich black muck in the valleys, 
to light and very dry soil, full of mica and sand, on the 
ridges and meadows. Where not packed hard, the latter is 
very porous, and the heaviest rainfall is quickly absorbed, 
or carried away on the surface. As a result, the valleys are 
always moist and rich in grass, and the slopes and ridges 
are always dry and warm. 
Streams and Ponds.—The Zoological Park contains about 
34 acres of still water, of which Bronx Lake comprises 25 
acres, Lake Agassiz 51% acres, Cope Lake, the Wild-Fowl 
Pond, and Beaver Pond together, about 3% acres. The 
two larger lakes are fed by the Bronx River, which drains 
a valley about 15 miles long. Even in the driest seasons the 
volume of water carried down by the Bronx River is suffi- 
cient to keep the lakes well filled. The areas of still water 
available for animal collections are very generous for an 
institution like this, and are highly prized. 
The Waterfall—aAt the lower end of Lake Agassiz, and 
about 300 feet above the Boston Road Bridge, is a natural 
waterfall nearly 12 feet in height, where the Bronx River 
falls over a rugged ledge of pink granite. In times of high 
