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Puddingstone EarthCache

Hidden : 05/06/2011
1.5 out of 5
1.5 out of 5

Size: Size:   not chosen (not chosen)

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Geocache Description:

Roxbury Puddingstone became the state rock in 1983. Nira Rock Park, with it's prominent outcropping of pudddingstone, is managed through a partnership between the Urban Wilds Initiative and Friends of Nira Rock.

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Roxbury Puddingstone forms the bedrock underlying most of Roxbury, Massachusetts, now part of the city of Boston and surrounding areas. In the 19th and early 20th centuries it was frequently used to construct walls and house foundations in the Boston area; some of the stone was quarried in Brighton and Newton, but the most extensive workings were those in Roxbury.

Puddingstone is an ancient river gravel which has been cemented into a hard rock by natural mineralization. The gravel was laid down in the beds of rivers hundreds of years ago. The individual round pebbles, which can still be seen, represent the various types of rock that existed in the area at that time. These include volcanic rocks, granite and quartzite. Over time the accumulation of younger deposits on top of the gravel eventually bonded the gravel together in the same manner as cement hardens to form concrete. This natural concrete was then squeezed and deformed by deep-seated earth forces and slowly unearthed by surface erosion. Some of this erosion was accomplished by the glaciers that existed here until as recently as 12,000 years ago.

To claim this unique EarthCache visit the park, locate the very obvious outcropping of Puddingstone and send a PM with the answers to the following questions:

1) What is the color of the matrix material?

2) Within an approximate 1x1 foot area estimate how many different rock/grain types are present?

3) Within eyesight of the park you can see many uses of puddingstone. Name one.

Optional: Post a photo of your visit to encourage other visitors.

Additional Hints (Decrypt)

Bcra sebz qnja gvy qhfx, npprff vf rnfvrfg sebz Aven Nirahr.

Decryption Key


(letter above equals below, and vice versa)