Sculpted by the ancient journey of a 1,000-foot deep glacier, the land underneath Prospect Park is composed of two basic geological features: a terminal moraine and an outwash plain.

A terminal moraine is the accumulation of large deposits of soil and rock left behind by the melting glacier. These deposits created "knob and kettle" terrain - a complex of hills and ponds caused by the movement of the glacier. Knob and kettle terrain offered deep porous soil to the forest developing on what would become the Park's east side; it also created hills and valleys which allowed for the construction of the Park's man-made watercourse.

An outwash plain is an area where sedimentary sand, gravel, and clay spread over the land, distributed by the flow of melting ice. An outwash plain left the Park with flat, sandy land over its southern third, allowing for construction of the Park’s 60-acre Lake.

The Design
The changes in the landscape brought about by the Park’s creation resulted from a complex combination of geology and the pioneering landscape architecture of design team Olmsted and Vaux. The isolated stand of remaining deciduous forest was enhanced to create a more continuous expanse of core woodlands, as well as a woodland buffer that separated the Park’s perimeter from the surrounding city. The Park designers also took advantage of the kettle ponds and the lowland plains for the development of the Park’s watercourse. A naturalistic stream channel feeding a 60-acre Lake was crafted to include a steep, forested Ravine and river’s edge habitats.

Olmsted’s plant vocabulary included both native and non-native species. Evergreen plantings were the least successful. Many of the exotic species of vegetation he used have since disappeared from the Park while others have been too successful, regenerating at the expense of native plant communities. The Long Meadow replaced swampy peat bog with rolling hilly turf punctuated by scattered specimen trees planted during the Park’s construction. Some parts of the Park, like the Long Meadow, are called meadows, but they are really mown turf. True meadows are grassy areas where the plants are allowed to grow, flower, and seed. They are beautiful to look at and provide important habitat for insects, birds, and small mammals. There are two "true" meadows in the Park: one by the Upper Pool in the Ravine and one on Lookout Hill.