APPLICATION OF LIDAR TO MAPPING AND INTERPRETATION OF MAINE'S COASTAL MORAINE BELT

Newly available lidar coverage provides fresh insights into the glacial landscape of southern Maine. Lidar imagery was compared with surficial geologic maps of the Waldoboro area in mid-coast Maine, and the Tunk Lake – Sullivan area in eastern Maine. These areas are within the belt of coastal moraines deposited in the sea during deglaciation. Lidar shows that moraines are extremely abundant across much of the region, as proposed by G. W. Smith’s deglaciation model. Many of the moraines in the Waldoboro quadrangles are subtle features, as little as 1-2 m high, and were previously unrecognized due to forest cover and/or limited access. The average spacing between moraine crests is fairly uniform within each cluster – typically 65-75 m but in a few places as much as 155 m. This regularity suggests annual deposition as proposed by Smith and others; and the inferred rates of ice-margin recession are similar to the 80-100 m/yr rates derived for southern NH by J. C. Ridge using the North American Varve Chronology. Lidar also shows late-glacial raised marine shorelines with unprecedented clarity. The highest shorelines in the mid-coast region occur at elevations of ~ 79-82 m and help define the upper marine limit in this area where there are few ice-contact marine deltas. Regressive shorelines are likewise evident on the lidar images. Delineation of the raised shorelines will facilitate location of associated sand and gravel deposits that resulted from marine reworking of glacial sediments. Lidar imagery of the coastal moraine belt also enables better ice-margin correlations on local to regional scales, including efforts to determine the extent of the Pineo Ridge moraine system in eastern Maine. Despite the limited area of present lidar coverage, available imagery has been coupled with field work to trace the Pineo Ridge system westward from Cherryfield. The cluster of moraines trends SW through northernmost Steuben, and is still robust but more segmented where it crosses T7 SD and Sullivan townships. However, lidar reveals that the moraines become smaller and mingle with numerous other minor moraines as they veer SSW into the ocean at Flanders Bay. This suggests the large moraines of the Pineo Ridge system may have formed in response to late-glacial climate conditions in eastern Maine and thus may be of relatively local significance.