The existence of six entrances to the Park renders it impossible to lay out an all-embracing "tour" for the visitor, and develop the Guide Book accordingly. The various collections will be handled in zoological groups, but the various groups cannot follow each other in zoological sequence. The table of contents and a comprehensive index will render each item of the subject matter quickly available.
The extreme length of the Park from north to south is 4,950 feet, or 330 feet less than one mile; and its extreme width is 3,120 feet, or three-fifths of a mile. Roughly estimated, one-third of the land area is covered by heavy forest, one-third by open forest, and the remaining third consists of open meadows and glades. The highest point of land in the Park is the crest of Rocking Stone Hill, the elevation of which is 94.8 feet above sea level.
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.