thumbnail

Modern sedimentary environments in Boston Harbor, Massachusetts

Journal of Sedimentary Petrology

By:
, , and
https://doi.org/10.1306/D42677D5-2B26-11D7-8648000102C1865D

Links

Abstract

Analyses of sidescan-sonar records supplemented by available bathymetric, sedimentary, subbottom, and bottom-current data reveal the distributions of the following three categories of sedimentary environments within the glaciated, topographically complex Boston Harbor estuary in Massachusetts. 1) Environments of erosion appear on the sonographs either as patterns with isolated strong reflections or as uniform patterns of strong reflectivity. These patterns define outcrops of bedrock or till and coarse lag deposits that are being scoured and winnowed by tidal- and wave-induced currents. Erosional areas are located primarily along mainland and insular shores, within large channels that have strong tidal currents, atop submerged ridges and knolls, and across much of the harbor entrance. 2) Environments of deposition are depicted on the sidescan-sonar records as smooth, featureless surfaces that have low to moderate reflectivity. Depositional environments are found predominantly over shallow subtidal flats and in broad bathymetric lows where tidal currents are weak. Sediments within depositional areas are organic-rich sandy and clayey silts that are accumulating at rates ranging from 0.01 to 0.11 g/cm 2 /yr or 4000 to 46,100 metric tons/yr. The cumulative mass of modern mud in harbor depocenters is 24.3 million metric tons. 3) Environments of sediment reworking constitute areas affected by a combination of erosional and depositional processes. They are characterized on the sonographs by mosaics of light and dark patches produced by relatively subtle and gradational changes in reflectivity. Reworked sediments have diverse grain sizes that overlap and are transitional between those of the other two sedimentary environments, and they are indicative of highly variable bottom currents.

Study Area

Additional publication details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Modern sedimentary environments in Boston Harbor, Massachusetts
Series title:
Journal of Sedimentary Petrology
DOI:
10.1306/D42677D5-2B26-11D7-8648000102C1865D
Volume:
61
Issue:
5
Year Published:
1991
Language:
English
Publisher:
SEPM
Contributing office(s):
Woods Hole Coastal and Marine Science Center
Description:
14 p.
First page:
791
Last page:
804
Country:
United States
State:
Massachusetts
City:
Boston
Other Geospatial:
Boston Harbor