The small Bellingham Basin, is a structural feature in eastern Massachusetts, which formed within older
Proterozoic
The Proterozoic () is a geological eon spanning the time interval from 2500 to 538.8million years ago. It is the most recent part of the Precambrian "supereon". It is also the longest eon of the Earth's geologic time scale, and it is subdivided ...
rock and contains
metasedimentary and
metavolcanic rocks dating the
Pennsylvanian Pennsylvanian may refer to:
* A person or thing from Pennsylvania
* Pennsylvanian (geology)
The Pennsylvanian ( , also known as Upper Carboniferous or Late Carboniferous) is, in the International Commission on Stratigraphy, ICS geologic timesca ...
, deposited between 323 and 298 million years ago. The basin is bounded by extensions of the
Mount Hope fault and a fault extending from the
Boston Basin.
The rocks in the basin metamorphosed to
greenschist facies on the sequence of
metamorphic facies
A metamorphic facies is a set of mineral assemblages in metamorphic rocks formed under similar pressures and temperatures.Essentials of Geology, 3rd Edition, Stephen Marshak The assemblage is typical of what is formed in conditions corresponding ...
and contain flattened pebbles.
References
Natural history of Massachusetts
{{Massachusetts-geo-stub