%0 Report %D 2008 %T Field Investigation of the Geology and Possible Pisolitic Bauxite Occurrence at Menemsha Hills Reservation, Martha’s Vineyard, Massachusetts %A Stephen B Mabee %A Panish, P. %K #MGSPub %K #MGSPubs %K #Minerals %K #Reports %K aluminum %K bauxite %K ferricrete %K glacial %K hematite %K Holocene %K Martha's Vineyard %K Menemsha Hills %K minerals %K ore %K oxides %K pisolite %K pisolitic %K precipitation %K reservation %K thrust faults %K Trustees %K Vineyard %X The Office of the Massachusetts State Geologist was asked by The Trustees of Reservations to make an assessment of an unusual deposit of what appears to be pisolitic bauxite or iron hardpan exposed on the beach at Menemsha Hills Reservation in Chilmark, Massachusetts. The formation occurs as thin 10-20 cm wide lenses extending from 0.5 to 6 meters in length. They are found most commonly along a 200 to 250 meter section of the shore in the intertidal zone. The intact lenses trend northeast at about 25° to 35° and dip at 61° to 75°. The material occurs in a variety of forms. These include hematite and clay rich botyoidal (grape-like) surfaces, as iron hardpan cementing together gravel and pebble-sized stones, and as 1-2 cm wide pisolites (concentrically layered round structures). Prepared for the Trustees of Reservations %I Office of the Massachusetts State Geologist %C Amherst, MA %G eng %U http://www.geo.umass.edu/stategeologist/Products/reports/FinalReport.pdf %9 4/2008