GLACIAL STRIATED BOULDERS (MILTON, DE) AND STRIATED COBBLE (NEAR OC, MD) ADD TO MOUNTING EVIDENCE OF GLACIATION ON THE MID-ATLANTIC COASTAL PLAIN AND RELATED AREAS

In 1970, the writer announced his glacial theory at the GSA/SE meeting in Lexington, KY entitled “On the Glaciation of the Mid-Atlantic Coastal Plain.” Hard to believe? Agassiz doubted until shown the evidence. Recently, striated boulders (str bldrs) and a cobble (cbl) were found near the seashore, 125 and 150 miles S. of the nearest Wisc Mor (WM) at Perth Amboy, NJ, prompting this review. Since 1970, 10 str bldrs and cbls were found from NJ to VA.

In NJ, Pre Wisc Qt deposits are mapped as glacial in the mountainous areas, 25 miles beyond the WM. But on the coastal plain (cstl pln) they have been mapped as non-glacial fluvial deposits since the 1890’s, when Professor Salisbury said the Hudson R. was the agent. He overruled his assistants’ suggestions to consider glaciation. He said the ice sheets fell into the sea. Did the Hudson by pass the sea, then flow uphill to El 200, surmounting the high dissected coastal plain and not gouging a canyon across it? Impossible!

As evidence, following are listed glacial features and characteristics of the Coastal Plain described by geologists for over 125 years, and some found by the writer: Rounded to angular up to 5 ft. boulders; a group of large boulders, one 15x6x2 ft in NJ; str bldrs, till outside the WM; sorted, unsorted and varve deposits; distorted, folded layers; river pebbles in crumbled saprolite near Susq R, MD; folded shale in NJ; older deposits mixed in Plst deposits; older sediment blocks in Plst deposits; soft shale slabs 60 miles from outcrops; gravel and bldr trains; erratic bldrs and soils; erratic 1-3 ft. bldrs on rock ridge, 200 ft. above Plst, N.J.; moraine, swell and sag topo with depressions; 5 ft. high esker, NJ; swamps; deposits up to El 200, NJ; deposits 180 ft. above DE R. Wilm DE; deposits sloping from El 130 to SL, Newark, DE; polished, str bldr (Arl) and str cbl (Qtco) VA; terrace deposits 100-200 ft. above rivers, u-shaped valleys (including Potomac R. MD). Much of this is not in the literature after 1917.

Striated bedrock, rare proof, had never been found in this area. In 2006, a str diabase boss was found by the writer near Rocky Hill, NJ. No combination of large swift ice rafting rivers, glacial outwash, jökulhlaups and peri-glacial activity can account for these existing features. These facts, not opinions, are proof of continental and valley glaciation on the Mid-Atlantic Coastal Plain Region.