Note
1. sand and gravel capping flat surface, top about 360 feet. 2. composition and structure: a/ thickness (past or present) not known, nor contacts at this place; b/ bedded with some current-bedding and perhaps imbrication of pebbles; c/ types, roughly in order of abundance: vein quartz, metamorphic vein quartz, pinkish quartz, quartzite, reddish sandstone (Triassic?), fine-grained sandstone, weathered serpentine (honeycomb rock), Paleozoic chert pebbles (fossiliferous), smoky quartz, Wissahickon (?) schist, decayed quartz-feldspar rock, coarse quartz-mica rock, sugary vein quartz; 3. size: max. about one and one-half feet; average max. about 4-6 inches; average about 2-3 inches for pebbles and cobbles; sand here pure shows excellent sorting, with 75% on 1/4 mm. sieve and 21% on the 1/8. 4. heavy mineral analysis shows a very small suite with about 50% zircon, 20% tourmaline, 20% staurolite, and scattered grains of sillimanite, rutile, kyanite. Almost nothing else is present; 5. points that are to be considered in discussion are: relation to other gravels of Philadelphia area; relation of gravel to flat area it covers; origin of gravel and sources of lithologic types; direction of currents; comparison with Cretaceous (?), Triassic, Pleistocene.
Sponsorship
This Digital Object is provided in a collection that is included in POWER Library: Pennsylvania Photos and Documents, which is funded by the Office of Commonwealth Libraries of Pennsylvania/Pennsylvania Department of Education.
