A view of a glacial scoured outcrop of gneiss and schist of the Manhattan Formation exposed by The Lake on Central Park's west side. The skyline of Midtown dominates the horizon.
USGS
http://3dparks.wr.usgs.gov/nyc/common/captions.htm
- A view of a glacial scoured outcrop of gneiss and schist of the Manhattan Formation exposed by The Lake on Central Park's west side. The skyline of Midtown dominates the horizon. USGS http://3dparks.wr.usgs.gov/nyc/common/captions.htm
- Manhattan Schist, Inwood Hill Park, Manhattan Island. The Manhattan Schist here is predominantly a massive quartz-plagioclase-biotite-garnet gneiss, and with varying amounts of muscovite, sillimanite, staurolite, and kyanite. The late Taconian metamorphic grade was K-feldspar + sillimanite, but during Devonian retrogression, muscovite, staurolite, and kyanite grew at the expense of sillimanite + garnet + K-feldspar + biotite. The outcrop we see by the footpath displays coarse garnet porphyroblasts in a dark, biotite-rich matrix, and muscovite is fine-grained and subordinate. This rock was only partially recrystallized during Devonian time, and largely preserves its Taconian fabric. Elsewhere, however, retrogression was more complete, and muscovite has grown to dominate the appearance of the rock. We will not take the time to find Devonian-age muscovite schist in outcrop, but several rocks placed alongside the footpaths are representative of the retrograded rocks. These irregular degree
- Generalized Precambrian and Lower Paleozoic Stratigraphy for the New York City region (modified after American Association of Petroleum Geologists COSUNA Charts (1983, 1986), Drake et al., 1996, Fisher et al., 1995, and Rodgers, 1985). http://3dparks.wr.usgs.gov/nyc/common/captions.htm USGS
- The Ramapo fault runs 70 miles northeast from Morris County, through Ramsey and Suffern and the Hudson Highlands, to Bear Mountain, N.Y. It follows the Ramapo River through the Ramapo Mountains and is actually a "braid of faults," or a system of cracks. http://www.earthinstitute.columbia.edu/news/story3_1_01.html
- Colorized version of the first geological map of Manhattan based on the work of J. F. Kemp (1887). The geological profile-sections were drawn parallel to streets in Manhattan with subsurface relationships in the southwestern part based on borings. Produced in an era when rocks were exposed in a rural setting in the north half of the island and when they were also being uncovered in excavations, Kemps sections are detailed. For the purposes of illustration, we have colored the Manhattan Gneiss as a single unit as Kemp originally intended. Notice that the scale of the profile-sections does not match that of the map. http://www.geo.sunysb.edu/lig/Conferences/abstracts-04/merguerian/Merguerians2004.htm
- Inwood Marble with siliceous layer in center. Coin on late vein is a quarter. http://pbisotopes.ess.sunysb.edu/reports/ny-city/index.html
- Photomicrograph in plane-polarized light of the Manhattan Schist (C-Om) showing an aligned intergrowth of biotite (bi), kyanite (ky), and muscovite (mu) in a fine-textured matrix of intergrown plagioclase (pg) and quartz (q). The foliation in this view is diagonal across the image. (Sample N217; South of George Washington Bridge approach, Manhattan; 1.6 mm field of view.) (From Merguerian, 2005.)
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