21 Formation Processes and Characteristics of Subglacial Bedforms beneath the Ice Sheets of Continental North America

Friday, 28 March 2008
8:00 AM - 10:50 AM

COMPOSITION AND SHAPE OF STREAMLINED BEDFORMS IN A PORTION OF THE WEEDSPORT DRUMLIN FIELD, NORTH CENTRAL NEW YORK

Paper number: 21-3
Program: THEME SESSIONS
Time: 8:30 AM – 8:50 AM

Authors

Abstract

A portion of the Weedsport drumlin field north of Cayuga Lake, NY contains flutes, and complex drumlins that depart substantially from the normal drumlins to the North, East and West.

Shape analysis, using length to with ratios measured from topographic maps and aerial photographs, and map analysis show that three distinct groups of elongate bedforms exist in this part of the drumlin field. Normal drumlins (L/W ratio less than 5:1) transition into complex drumlins (normal drumlins with superimposed flutings) which transition into fluted drumlins (L/W ratios between 15:1 and 63:1). These transitions occur both parallel to, and orthogonal to, regional ice flow.

All three types of streamlined bedforms are composed of a dense massive till that ranges in color from dark purple to brown. Grain size analysis of 57 till samples collected from deep exposures in the three types of streamlined bedforms demonstrate no significant variation in texture. Therefore, till texture does not control bedform shape in this portion of the drumlin field.