[Rockhounds] NASA Image Unveils One of the World’s Rarest Geologic Wonders Hidden in Boston Harbor

[Kreigh Tomaszewski]

NASA’s latest image of Boston Harbor, showcasing its remarkable drumlin
islands, has captivated both scientists and nature enthusiasts. Captured on
July 19, 2024, by the Landsat 8 Operational Land Imager, the photograph
reveals a rare geological formation that few people are aware of. This
striking visual, part of a detailed study shared by the NASA Earth
Observatory
<https://earthobservatory.nasa.gov/images/154204/the-drumlin-islands-of-boston-harbor>,
highlights the significance of these islands, which are a geological
treasure formed over 20,000 years ago by glaciers during the Wisconsin
Glaciation.

Boston Harbor, now a bustling hub of history and tourism, was once shaped
by a vastly different natural force—glaciers. The drumlin islands, a series
of elongated hills formed by glacial debris, were created more than 20,000
years ago during the Wisconsin Glaciation. At the height of this icy
period, massive glaciers up to a mile thick blanketed the land that now
forms the Boston Harbor Islands National and State Park.

As the glaciers began to retreat, they left behind piles of sediment and
debris that formed these distinctive drumlins. Today, these islands are
considered one of the most unique geological features on Earth, with only
two other known drumlin fields found worldwide in Clew Bay, Ireland, and a
similar formation in Canada
<https://dailygalaxy.com/2025/04/the-most-extreme-rogue-wave-ever-recorded/>.
These islands are not just geological marvels—they represent a frozen
moment in time, forever etched into the landscape of Boston Harbor.

While drumlins can be found across the globe, the ones in Boston Harbor are
distinct due to their partially submerged nature. These islands form the
only known partially submerged drumlin field in North America
<https://dailygalaxy.com/2025/04/geoscientists-discover-north-americas-crust-is-slowly-being-sucked-into-earths-mantle/>,
offering scientists a rare opportunity to study the effects of glaciation
on the land and the environment.

https://dailygalaxy.com/2025/04/nasa-image-geologic-wonders-boston-harbor/