Geology and Geophysics of the Rittenhouse Gap Iron Mine and the Mid-Atlantic Iron Belt, Berks County, Pennsylvania
(and beyond)

Kurt Friehauf - Kutztown University of Pennsylvania


Hopewell Furnace - photo by National Park ServiceRittenhouse Geophysics - MarchBeginning in colonial times and continuing through the Civil War, eastern Pennsylvania was an important source of our nation’s iron, feeding furnaces with ore to make cannon and machinery.  Most of this iron came from relatively small deposits of a few thousands of tons of magnetite ore in very old granitic and metamorphic rocks, although several multi-million ton orebodies also occur in the area in younger limestones.  The belt of mines stretches through northern New Jersey and into southern New York and is known as the Mid-Atlantic Iron Belt.

Like many iron deposits in eastern Pennsylvania, the Rittenhouse Gap mine closed in the early 1900’s and nature has made great inroads in reclaiming the landscape.  Although iron mining in eastern Pennsylvania and New Jersey ceased decades ago, the question of how the iron deposits in this region originally formed, is a matter of active debate in the geological scientific community.

At the core of the debate lie three key questions:  1) When did the deposits form?  2) What was the source of the hot waters that deposited the iron?  And 3) Are all of the small deposits related to one big, crustal scale geothermal system, or do the deposits represent isolated events?

Rittenhouse Gap - Mappin without digging in snowI've been working with undergraduate students for the past few years to try to unravel this little mystery.  I've been very, very lucky to have the help of Robert Smith of the Pennsylvania Geological Survey and Richard Volkert of the New Jersey Geological Survey - both are extraordinary guys.  Limited exposures and metamorphosed rocks make it a tough nut to crack, but we're having fun working at it!

on to Geological background

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