By Valerie Perini

Boston Harbor, with its many rocky islands and outcrops, has been an important geological study site for centuries. Building on this work, a team of geologists including Marine and Environmental Sciences Professors Martin Ross and Richard Bailey have recently published a book chapter highlighting important features of Boston Harbor Island geology. 

In the chapter, published in the New England Intercollegiate Geological Conference’s Guide to Field Trips in Southern New England, the researchers describe, compare, and analyze the composition of bedrock formations around the Boston Harbor Islands and Nahant. Specifically, the researchers report on the chemical composition of the rocks of the Boston Harbor Islands, comparing them to those of Nahant. The study also describes how the elemental composition of certain rock formations, known as sills and dykes, offer evidence of the tectonic activities that led to their formation. Finally, the researchers describe how they’ve used evidence about chemical composition and other rock characteristics to construct a timeline describing the age and formation processes of rock layers. 

This work, supported by the U.S. Geological Survey, Massachusetts Geological Survey, and the National Parks Service, offers a unique tool for exploring the fascinating rock formations in and around Boston Harbor.