EPOD - a service of USRA
The Earth Science Picture of the Day (EPOD) highlights the diverse processes and phenomena which shape our planet and our lives. EPOD will collect and archive photos, imagery, graphics, and artwork with short explanatory
captions and links exemplifying features within the Earth system. The
community is invited to contribute digital imagery, short captions and
relevant links.
Archive - Glacial Evidence in Central Park
April 09, 2022
6a0105371bb32c970b01b7c6def3d2970b
Every weekend we present a notable item from our archives.
This EPOD was originally published on 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 glaciation, 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.
Nycglacialrock2
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.
* Glacial Erratic, Central Park Coordinates: 40.769358, -73.975933
Related EPODs
Archive - Glacial Evidence in Central Park Muonionalusta
Siderite Sample Archive - Mud Cracks near Trona, California
Rainbow Pyrite Archive - Naatsis’aan Archive - Upheaval
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More...
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