Reidentifying Depositional, Solifluction, “String Lobe” Landforms as Erosional, Topographic, Steps & Risers Formed by Paleo-Snowdunes in Pennsylvania, USA

Abstract

A controversy arises concerning relict, ubiquitous, depositional, solifluction, “string lobe” landforms in the Ridge and Valley province of Pennsylvania, reported by other investigators. A distinguishment is made here by defending an original interpretation of the particular landforms which identified these as snowdune meltwater-eroded depressions formed within colluvium during cold phases of the Pleistocene Epoch. Hence, the landforms are reassessed as “steps & risers” in this study which is jargon associated with nival erosion. The reidentification is warranted in the study because of multiple lines of evidence including: the landforms’ detailed geomorphology and sedimentology; the landforms having a highly, unusual, very repetitive, NE-SW orientation; and the landforms incurring a striking, gravity-defying, characteristic of running-water erosion repeatedly occurring irrespective of the steepest part of the general slope. Besides the evidence offered here, the study also gives insight, resolutions and re-confirmations in order to establish absolute identification while differentiating between discussed, periglacial, relict landforms. An agreement is reached however, regarding actual, true solifluction landforms occurring only on slopes that point in a particular, general direction.