Surficial Geology Map of Quincy, Massachusetts, 1964
From the thesis of Donald E. Reed, S.B., 1964,
MIT Department of Geology and Geophysics
As an MIT undergraduate, Donald E. Reed (S.B., Course XII, Geology and Geophysics, 1964) spent the summer of 1964 conducting fieldwork in preparation for his bachelor’s thesis, “A Surficial Geology Map of Quincy, Massachusetts.” The principal product of his research was an elaborate map of the surface geology of Quincy, a suburban community south of Boston. Using a printed topographical map as a base, Reed painstakingly added an overlay of colored pencil, indicating zones in which the various geological features he identified in his survey were predominant. He analyzed the features and explained the map in an accompanying text in the thesis. One of the challenges he faced in reconstructing a town’s geology was that “the mapping was complicated by the lack of conspicuous land forms . . . where man has extensively reworked the surface soils by cutting, filling and grading operations.” One of his expressed goals was to delineate all areas of fill, which are “so important to the architect, engineer, and contractor.” While working on the thesis, Reed received valuable technical advice and feedback from two members of the firm of Haley and Aldrich, specialists in underground engineering and exploration of subsurface conditions. The firm hired him as an engineer after graduation.
The survey relied on a variety of sources, including library research, examination of open excavations, conversations with contractors about what materials they encountered when digging, interviews with homeowners, inspection of bedrock outcrops, and five hundred test boring logs stored in the offices of contractors and among the files of the City Engineer of Quincy. Reed concluded that “foundation borings,” taken to determine soil conditions beneath proposed structures, were among his most reliable sources. An 1867 U.S. Coast Survey map showing salt marshes and peat bogs (subsequently filled) also proved indispensable.
Much of the topography and surface geology of New England was sculpted by the last of the four great Pleistocene glaciations, when Quincy and the rest of the region were covered by an ice sheet two to three miles thick. “The enormous pressure differentials existing in a sheet of ice of this thickness caused the basal portion of the ice to flow by slow plastic deformation, . . . [removing] most of the preexisting soils and great quantities of the underlying bedrock. These materials were reworked into the body of the ice and transported with it.” Surface features left behind after the recession of the ice differed widely, depending upon such variables as the direction of ice flow, pressure, and the characteristics of the parent rock. The Boston area is famous for drumlins, hills composed largely of clay derived from shale or slate, in which the author took a special interest. The map shows normal elliptical drumlins in Quincy as well as drumlins that have coalesced into more complex configurations, such as President’s Hill.Object of the Month: November 2003
The Institute Archives and Special Collections, a division of the MIT Libraries, houses over 101,000 theses dating back to 1868. The theses are preserved as a record of work done by students to complete requirements for a degree; as a reservoir of original research that can be built upon by future generations of scholars; and as a way of tracking historical trends in the sciences, engineering, and other fields.