Glacio-Periglacial Landforms within the Susquehanna Great Bend Area of New York and Pennsylvania

Abstract

Previous attention has been called to the morphology of the glaciated Appalachian Plateau, including periglacial phenomena (Coates, 1970; Conners, 1969). This paper deals with an unusually well-developed hierarchy of small landforms in the Great Bend area of the Susquehanna River. Essential properties of these features include: (1) concentration in N-S valleys, (2) till composition, (3) concavo-convex form, sometimes ending in a hill on the valley floor, (4) alternation with steep, truncated bedrock spurs, (5) a col in the interfluve at their head. These characteristics could be explained by the following sequence of events. A prior fluvial landscape was eroded with tributary streams forming lateral valleys that head in cols along the divides. The main stream flowed south between interlocking spurs. Ice then widened the valley, leaving truncated spurs and a straightened stream. Deposition of locally derived till filled tributary valleys, similar to till shadows (Coates, 1966). In periglacial conditions, while nivation was widening the tributary valley heads, solifluction in the unstable till was forming the concavo-convexities that alternate with the truncated bedrock spurs. The hierarchy of forms range from minor convexities to small hills on the main valley floor. Thus, the features are primarily of periglacial origin, but owe their development and position to prior subaerial and glacial events. The cycle may have occurred during more than a single glacial episode. The recession of bedrock spurs and the valley floor convexity of the till features have caused a reversal in stream sinuosity of the main valley.

Hydrogeology of Valley-Fill Aquifers and Adjacent Areas in Eastern Chemung County, New York

“…Stratified-drift deposits that are potential sources of groundwater supply extend beyond surficial stratified deposits in some valley areas where till overlies sand and gravel. Till may have been deposited directly over older permeable sediments during glaciation or may have slumped over outwash deposits from unstable valley wall positions after glaciation (Denny and Lyford, 1963, p. 15-20;King and Coates, 1973).…”

Hydrogeology of the Susquehanna River valley-fill aquifer system and adjacent areas in eastern Broome and southeastern Chenango Counties, New York

“…Till knobs in some north-south oriented "beaded valleys" are interpreted as representing moraines that record pauses in the retreat of glacial ice that were later smoothed by periglacial activity (Braun, 2002(Braun, , 2006c. Other till features in small valleys were interpreted as glacial or periglacial landforms (King and Coates, 1973). They documented concavo-convex landforms of till in glacially-widened north-south oriented tributary valley bottoms in the southern part of the study area (east of Windsor, N.Y.).…”

“…In addition, low till hills of different origin have been noted in primarily northsouth-oriented tributary valleys. The small hills or lobes have been interpreted as a result of downslope movement of till from hillside hollows into the tributary valley during periglacial periods (concavo-convex landforms; King and Coates, 1973) and as recessional moraines, marking upland stillstands of the ice margin (Braun, 2002(Braun, , 2006c.…”

Glacial Geomorphology

“…F or example King and Coates (1973) in analysis of a rather unique set of hills and mounds in the Great Bend area ascribe them to a glacio-periglacial origin (Fig. It does seem dear, however, that all such hills cannot be lumped into a single category, but instead are polygenetic.…”

“…Not only are periglacial features found in the southern border of the section, but they also notably occur in the Great Bend area (Harrison,1966;King and Coates;Coates and King,1973). Here solifluction slopes are prevalent, patterned ground and block fields occasionaly are present, and even tors and rock cities occur on som\!…”