Titusville till stratigraphy and weathering complications, Booth Run section, Mercer County, Pa.
Gary M Fleeger, Pennsylvania Geological Survey, 3240 Schoolhouse Road, Middletown, PA 17057-3534
White and others (1969) indicated that the Titusville Till occurs in as many as five till sheets separated by beds of sand and gravel, formed by minor pulsations of the Titusville glacier. They also suggested that perhaps the Kent Moraine (a Titusville glaciation feature) resulted from the stacking of these Titusville Till sheets.
The 70-foot high Booth Run Section has all five of the Titusville Till sheets, but is many miles behind the Kent Moraine. Evidence suggests that the five till sheets may have been deposited by up to three glacial advances, and are not all Titusville tills. The third sheet (Titusville 3) has 3 feet of oxidized till at the top. Titusville 2, directly above the sand between Titusville 2 and 3, is unoxidized. This may indicate a period of weathering between the deposition of Titusville 2 and 3, suggesting that separate advances deposited them. Alternatively, the oxidation at the top of Titusville 3 may be related to the superjacent sand bed, as described below.
Titusville 3 and 4 are higher in carbonate (> 6%) than is usually found in the Titusville Till, and higher than any other till in the section. They may correlate with the Keefus Till (White, 1982), which is high in carbonate. The typical red coloration of the Keefus Till may have been eliminated by dilution with gray bedrock as the Keefus glacier advanced across the Allegheny Plateau. Titusville 5, at the base of the section, is low in carbonate, suggesting that an advance separate from the one that deposited Titusville 3 and 4 may have deposited it.
Titusville 1 and 2 probably correlate with the Titusville Till. Titusville 3 and 4 may correlate with the Keefus Till. It is more difficult to determine which pre-Keefus till correlates with Titusville 5.
The tills in this section display some weathering phenomena that can complicate till identification and interpretation. There are two weathering sequences that grade downward from oxidized till, to oxidized till with isolated unoxidized till pods, to unoxidized till with oxidation only along joints, to completely unoxidized till. These two sequences occur through Titusville 1 and 2, and Titusville 3 and 4. In addition, oxidation frequently extends outward from the sand beds into the subjacent and superjacent tills. These phenomena disrupt the “normal” weathering sequence of a till.
Poster paper presented at the 40th Annual Meeting of the North-central Section Geological Society of America, Akron, Ohio, April 20, 2006.
Photo by Gary Fleeger, PaGS.