23-04-2025
NASA Image Reveals Boston Feature That's 'One of Only Three in the World'
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NASA Earth Observatory has unveiled a new image of Boston Harbor's drumlin islands, highlighting these rare geological formations—one of only three worldwide—that were carved out by glaciers more than 20,000 years ago.
Captured by the Landsat 8 Operational Land Imager on 19 July 2024, the photograph shows an aerial view of the harbor, and the 34 islands and peninsulas that form the National and State park, drawing attention to its historical and cultural importance.
The space agency explains that during the Wisconsin Glaciation—which began between 100,000–75,000 years ago and ended about 11,000 years ago—a massive ice sheet, more than one mile thick in places, entirely covered the land that is now occupied by the small islands.
As the icy coat melted away, it left behind piles of sediment and glacial debris in hundreds of elongated, streamlined hills known as drumlins, which were later partially submerged by rising sea levels and turned into tiny islands.
Today, several of these drumlin islands make up part of the Boston Harbor Islands National and State Park, which works to preserve many distinctive geological, historical, and natural resources in the area.
Aerial view of the Boston Harbour drumlins shared by NASA.
Aerial view of the Boston Harbour drumlins shared by NASA.
NASA Earth Observatory image by Wanmei Liang, using Landsat 8 - OLI
According to NASA, these little glacial islands are the only partially submerged drumlin field in North America and one of only three in the world. A similar example can be spotted in Clew Bay, Ireland.
According to local folklore, there are about 365 drumlin islands in the Irish site, one for every day of the year.
Studying the formation of these islands has given scientists new insights into the role that glaciers have played in shaping many existing land-forms.
Jasper Knight, a geoscientist at the University of Witwatersrand, in South Africa, told NASA back in 2016: "Previous ideas of slow, steady advance, or retreat, really don't hold. Glaciers are dynamic."
Only four of the Boston Harbor drumlin islands, Deer Island, Nut Island, World's End and Webb Memorial, are accessible by car, while four others, including Spectacle Island, Georges Island, Peddocks Island and Thompson Island are served by seasonal ferries, and several more are accessible by private boat.
The drumlin islands feature diverse ecosystems including salt marshes, sandy beaches, sea-grass beds, tidal pools, mudflats, grasslands and hardwood forests—alongside a wide range of wild animals and marine life, including mussels, barnacles and dozens of mammals, birds, reptiles and amphibians.
They also boast several historical landmarks, including the Boston Lights, America's oldest operating lighthouse, located on Little Brewster Island, open since 1716, and Fort Warren, a civil-war-era fortress on Georges Island.
The fort was used as a prison for confederate officers and government officials during the civil war, and it's known for housing confederate vice president Alexander Stephens.
Another major historical landmark is Long Wharf, opened in the 1720s, which once served as a hub for Boston's maritime trade, and is now used by recreational boats.
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