Topography.—Speaking broadly, the Zoological Park is composed of granite ridges running from north to south. In many places their crests have been denuded of earth by the great glacier which once pushed its edge as far south as New York City. In the valleys lying between these glacier-scraped ridges, great quantities of sandy, micaceous soil have been deposited; but in one spot—the Wild-Fowl Pond—what was once a green, glacial lake fifteen feet deep, presently became a vast rock-walled silo filled with vegetable matter and a trembling bog of peat. Everywhere in the Park glacial boulders of rough granite or smoothly rounded trap-rock, varying in size from a cobble-stone to the thirty-ton Rocking Stone, have been dropped just where the warm southern sun freed them from the ice. The Park contains thousands of them, many of which have been removed from walks and building sites only with great labor. In three of the four principal valleys of the Park, bogs have been converted into ponds, and in the largest and deepest of all lie Bronx Lake and Lake Agassiz. The bed-rock underlying or cropping out in the Park exhibits pink granite, gray granite, rotten gneiss, and quartz in bewildering variety. Occasionally in trench-digging a ledge is encountered 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 “ 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 88 feet Of the Reptile House 78 “ Of the Lion House 64 “ Of the Aquatic-Bird House 57 “ 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.