Beacon Hill end moraine, Boston: new explanation of an important urban feature

Edited by: Donald R. Coates



The usefulness of geology to engineers is in direct proportion to how well it helps us predict the subsurface; these predictions, in turn, depend on our knowledge of the geomorphic processes that molded the terrain. The uncertainties of interpretation are particularly great in glaciated terrain because our understanding of both glacial processes and history is so incomplete, a fact well illustrated in Beacon Hill. Recent construction activities in the eastern part of the hill, until now classified as a drumlin, have shown that it is better interpreted as an end moraine formed by a Wisconsonian glacial readvance. Instead of the firm till that was anticipated as foundation material, excavations exposed a complex of sand, gravel, and clay, with only minor zones of till. The structure of these deposits strongly suggests that originally they were plates of the glacial bed that froze to the glacier and were transported englacially. Thrust faulting and other deformations are glacial structures formed within the ice in the glacier's terminal zone. In spite of the complex englacial history, these deposits lost little of their original appearance and intergranular relationships. Upon deglaciation, the frozen moraine thawed, and slumping formed complex secondary structures on the ridge's lower flanks.

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Additional publication details

Publication type Book chapter
Publication Subtype Book Chapter
Title Beacon Hill end moraine, Boston: new explanation of an important urban feature
Volume 174
Year Published 1976
Language English
Publisher Geological Society of America
Publisher location Boulder, CO
Description 14 p.
Larger Work Type Book
Larger Work Subtype Other Government Series
Larger Work Title Urban Gomorphology (Geological Society of America, Special Paper 174)
First page 7
Last page 20
Country United States
State Massachusetts
City Boston