The Geology of the Marginal Way
In Ogunquit, Maine
Stone walls across New England
Pawtuckaway State Park
The Pawtuckaway Mountains in New Hampshire are a small, rocky, circular range. They form the outline of an ancient volcanic ring dike, dating from 130—110 million years ago (Cretaceous era).
Ossipee Mountains ring dike complex
More amazing geology in New Hampshire.
Giant dikes in northeast America
A dike (or dyke) is a sheet of rock that is formed in a fracture in a pre-existing rock body. Dikes can be either magmatic or sedimentary in origin. See Giant Dikes in northeast America
Geological History of Jamestown, Rhode Island
Building the Northern Appalachian Mountains and New England
The Appalachians are a complex mix of mountains formed by a series of continental collisions that took place over a period of more than 1 billion years.
This page focuses on important mountain-building and landscape altering milestones in the history of the Northern Appalachians and New England. It utilizes a set of illustrative cross sections to depict the cumulative effects of these milestone events. The example cross-section runs parallel to, but slightly north of the present southern coasts of Connecticut, Rhode Island and Massachusetts, and extends westward into New York state and eastward beyond Cape Cod. Each geological event mentioned on this page is described more fully on other pages on this site; and those pages, in turn, have links to external resources.
Each of these mountain building events (orogenies) included incorporation of new land masses seaward of the former coast line, distortion of existing land forms and metamorphosis of existing rocks. Erosion of the each newly-formed mountain chain resulted in deposition of massive amounts of sediment – both inland and along the coast.
Over the more recent past (tens of thousands of years) the region has been further shaped by two major glacial advance and retreat cycles.
Hot magma upwelling beneath New England
The following is from “Huge Bubble of Hot Rock May Be Rising Under New England”, Erin Blakemore, National Geographic, 12/17
Researchers at Rutgers University and Yale University have used an array of seismic sensors to reveal what is happening beneath New England… geologists use seismic vibrations caused by earthquakes to visualize the features within rock. Sensing how fast seismic ripples move, for instance, provides details about the structure and temperature of Earth’s mantle.
Levin’s team studied data from EarthScope, a National Science Foundation program that deploys hundreds of geophysical instruments across the United States. The project’s Transportable Array, a temporary network of seismic sensors, made its way around the country starting in 2007. The array picked up readings from small earthquakes and observed the motions of seismic waves in various regions.
The team piggybacked off previous research showing a relatively hot spot beneath New England’s upper mantle. Using data from EarthScope, they then observed a localized plume of warm rock beneath central Vermont, western New Hampshire, and western Massachusetts—and found geologic evidence that it’s on the move….
The upwelling is likely tens of millions of years old… For now, it certainly hasn’t gotten close enough to the surface to shape New England’s geography or create a volcano. “Maybe it didn’t have time yet, or maybe it is too small and will never make it,” says Levin. “Come back in 50 million years, and we’ll see what happens.”
Seismic evidence for a recently formed mantle upwelling beneath New England
Vadim Levin Maureen D. Long Peter Skryzalin Yiran Li Ivette López
Geology (2017) November 29, 2017. DOI: https://doi.org/10.1130/G39641.1
In this figure, strength of mantle flow is shown along with the colored map of seismic wave speed at 195 kilometers (121 miles) beneath the Earth’s surface.
The warm colors indicate lower speed, implying that rock in those regions is less dense, likely warmer and rising toward the surface.
The key finding is that mantle flow indicators are smallest above the warm region, likely because warmer rock flows upward and disrupts the horizontal flow.
Credit: Vadim Levin/Rutgers University-New Brunswick
Teacher Guide to Geology of the Northeastern USA
This guide covers regions based on natural geological divisions:
Region 1: Inland Basin
Region 2: Appalachians/Piedmont
Region 3: Coastal Plain
Region 4: Exotic Terrane
Also see the larger teacher friendly guide to the Earth Science of the United States
2016 Massachusetts Science and Technology/Engineering Curriculum Framework
College Board Standards for College Success: Science
2006 Massachusetts Science and Technology/Engineering Curriculum Framework
Benchmarks for Science Literacy, AAAS