Glacial Evidence in Central Park

September 25, 2014


Photographer: Bruce Gervais
Summary Authors: Bruce Gervais; Jackie Phillips

There's ample evidence of New York City’s glacial history throughout Central Park. The top photo shows two glacial erratics. These large boulders were transported by moving ice at the height of the Wisconsin glaciations, around 20,000 years ago. During this time the Laurentide ice sheet covered what is now New York City to a depth of about 1,000 ft (300 m). As the ice sheet flowed over the landscape it smoothed the bedrock through abrasion and plucked fragments of rock from the ground. These plucked fragments were incorporated into the base of the moving ice and transported by it. After the ice sheet melted, some 12,000 years ago, many fragments were scattered throughout the landscape.


The lower photo shows an elongated asymmetrical landform called a roche moutonnee. The axis of roches moutonnees indicates the direction of ice flow. In this photo, the ice flowed from left to right. These landforms are ubiquitous in the park and were cleverly incorporated into its design. Photo taken on July 22, 2014.

Photo details: Top - Camera Maker: Panasonic; Camera Model: DMC-TS3; Focal Length: 4.9mm (35mm equivalent: 28mm); Aperture: f/3.3; Exposure Time: 0.0063 s (1/160); ISO equiv: 100. Bottom - same except: Focal Length: 8 mm; Aperture: f/4.5; Exposure Time: 1/80 s; ISO equiv: 160. Photo stitch program: Microsoft ICE.