Although many of Prospect Park’s landscape features were man-made, the Park has geology to thank for much of its natural beauty. Fifty thousand years ago – in a period known as the Pleistocene Epoch – the land beneath the Park was buried under a sheet of ice 1,000 feet thick. During this Ice Age, North and South America were submerged under slowly shifting glaciers. In the vicinity of New York, the Wisconsin Ice Sheet crept slowly south, dragging along detached bedrock, sediment, clay and soil.
When the climate began to warm 20,000 years later, the ice retreated, leaving a belt of hills (known as a terminal moraine) that runs through Queens, Brooklyn, and Staten Island. The northern edge of Prospect Park lies on this ridge, on land too steep for easy farming but well-suited for a Park complete with rich woodlands, steep ravines, and hilly meadows. The southern edge of the Park was built on crushed rock and gravel left behind by the melting glacier. This outwash plain would one day serve as the site for Prospect Park’s 60-acre Lake.
The Wisconsin Ice Sheet also left behind depressions in the land known as "knob and kettle terrain." These "kettle ponds" formed the geological surface necessary to create the Park’s watercourse, beginning with Fallkill Falls and continuing into the Ravine, Lullwater and the Lake.
Prospect Park is also the site of the last remaining indigenous forest in Brooklyn. After the climate warmed and the glacier retreated, grasses and mosses grew in its place and their root systems held the sand firm. Successive generations of dead plant material provided organic matter and nutrients to the developing soil. The soil accumulation, combined with continued warming trends, enabled trees to grow. Thick forests began to prevail about 8,000 years ago and, as the vegetation grew and the warming continued, diverse species of wildlife spread from the south and new ecosystems were born.
Prospect Park’s ecosystem emerged from a complex intermingling of geology and design. Unfortunately, despite taking thousands of years to create, the natural environment can become threatened in a relatively short period of time. That is why restoration and other landscape management techniques are so crucial to the continued health of this natural oasis, flourishing in the midst of intensely urbanized surroundings.