Above and Below Features

This will be the page where we will store the images you send for "Feature of the Week." Click on the thumbnails below for high resolution versions of the images. Click on the link under the thumbnail to go to a description of the feature.





Glacial Erratic,


Bedrock from Black Rock Beach, Cohasset, Massachusetts

We are defining bedrock as rock that is permanently attached to the surface of the Earth. It is a connected part of the crust. Return to top.


Dike from Sandy Beach, Cohasset Massachusetts

We are defining a dike as a semi vertical intrusion in another rock. The dike must always be younger than the rock it is intruding. If the intrusion is horizontal, the intrusion is called a sill. Dikes are usually igneous in origin. Return to top.


Veins from Sandy Beach, Cohasset, Massachusetts

We are defining a vein as a line in a rock, usually smaller than a dike,  filled with a mineral deposit . In most cases this material was deposited in the crack by having minerals precipitate (fall out) of a water solution. Return to top.




                                                                                       Marilyn Kozodoy Photograph


Glacial Erratic  from the Flume Gorge in New Hampshire.

 Erratics are boulders that were dropped by the glacier as it melted. They usually are very different from the bedrock under them. Return to top.


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