Brookline Member included in Roxbury Conglomerate of Proterozoic Z to earliest Paleozoic age. Members of Roxbury are not separately mapped but are mentioned.

Source: GNU records (USGS DDS-6; Reston GNULEX).

Authors state, "...historic stratigraphy and stratigraphic units of the Boston basin are suspect." They suggest that the only formal nomenclature that should be retained is Boston Bay Group, undifferentiated, and perhaps the Weymouth Formation and the Braintree Argillite. Units within the Boston Bay Group--the Cambridge Argillite, and the Brookline, Dorchester, and Squantum (Tillite) Members of the Roxbury Conglomerate--were defined largely on the basis of the percentage of conglomerate, diamictite, argillite, sandstone, siltstone, tuff, and matrix present. Authors believe that recognition of these units in the field is nearly impossible and propose a facies-derived model for the Boston basin. They suggest that the Boston Bay Group was deposited in a submarine fan/slope/apron environment.

Source: GNU records (USGS DDS-6; Reston GNULEX).

Brookline Member of Roxbury Conglomerate contains clasts of Dedham Granite, quartzite (probably derived from Westboro Formation), and volcanic rock from underlying Mattapan Volcanic Complex. Contains mafic volcanic rocks of Brighton Melaphyre [shown on State bedrock map of Zen and others, 1983, as "Melaphyre in the Roxbury Conglomerate]. Age is Proterozoic Z and possibly Early Cambrian. Report contains geologic map and cross sections. [Chapters A-J in U.S. Geological Survey Professional Paper 1366 are intended as explanations and (or) revisions to 1:250,000-scale MA State bedrock geologic map of Zen and others (1983).]

Source: GNU records (USGS DDS-6; Reston GNULEX).