[10]The black color is due to the inclusion of finely disseminated carbonaceous material (animal and plant remains) within the rock.
[11]This splitting or cleavage was produced after the layers had hardened into rock. The cleavage planes were produced when the rocks were subjected to pressures too great to withstand. In some places these cleavage planes do not parallel the layers.
[12]According to the basic geologic law, the Law of Superposition, younger rocks (those deposited last) are always found resting on older rocks (those deposited before the younger). The only time that this is not true is when either breaks (faults) or folds in the earth’s crust place the layers in an inverted order, as in the case here cited.
[13]The fault plane of a high-angle fault forms a large angle (generally from 30 to 90 degrees) at its intersection with an imaginary horizontal plane. The plane of a thrust fault, or low-angle fault, forms a small angle (generally less than 30 degrees) at its intersection with an imaginary horizontal plane.
[14]This is the Burlington till (Stewart, 1961) and was deposited from the Burlington Ice Lobe during its period of wasting. The till is a hodge-podge mixture of clay, sand and pebbles and is usually brown in color.
[15]A kame is a mound or ridge of poorly sorted (sometimes well-sorted, that is, made up of all the same sized particles) water deposited materials. Most kames are ice-contact features; that is to say, the materials which make up the kame were deposited in contact with a glacial ice surface. The Mt. Philo kame may be the filling of an ice-free area during the final melting of the glacial ice.
[16]Delta is the name of the fourth letter of the Greek alphabet, the capital form of which is an equilateral triangle. The triangular-shaped tract of land formed by the deposit of river sediment at river mouths is named for the triangular shape of the capital Greek letter delta.
—Retained publication information from the printed edition: this eBook is public-domain in the country of publication.
—In the text versions only, text in italics is delimited by _underscores_.
End of the Project Gutenberg EBook of The Geology of D.A.R. State Park, Mt. Philo State Forest Park, Sand Bar Sta, by Harry W. Dodge, Jr.