Glaciation

Another great controversy of 19th-century geology concerned the origin of the loose sediments strewn across the bedrock of much of the northern latitudes, including Connecticut. Deposits of sand were often observed to lie on high ground, well above the height that a flooding river could reach. Even more puzzling were the huge, sometimes house- sized boulders scattered willy-nilly across the countryside. Many of the boulders clearly were derived from bedrock miles distant from their current resting places. Because of their erratic distribution with little regard to topography, these out-of-place boulders came to be called "erratics . " In addition, wherever excavation for construction removed the surface smear of sediment, the face of the bedrock beneath was found to be smooth and hard, almost polished in appearance, with many parallel scratches as if some heavy object had been dragged across it.

The earliest geologists looked to the Bible for an explanation, and they attributed these features of the land (in addition to the origin of fossils) to the devastation of Noah's flood. The Bible tells that "the waters prevailed exceedingly upon the Earth; and all the high hills that were under the whole heaven were covered . "' Deposits of sand and gravel found high above modern rivers could easily have been left by a flood of such magnitude. The smoothed surface of the bedrock could have been polished by the rush of water as it finally drained from the land. One early Connecticut geologist, James Gates Percival, interpreted rounded, hill-sized heaps of sediment (drumlins) as vortices in the terrible flow of draining water. The flood explained enough observations that, in the early 1800s, the Noachian deluge (as it was called) was widely regarded as an established scientific fact.

Although the Noachian theory explained many observations, it did not solve the puzzle of the many parallel scratches incised on the bedrock surface. Flowing water does not scratch bedrock - it shapes and smoothes it, which is quite different from scratching. Nothing equivalent to these fine striations could be seen forming in streams and rivers anywhere, suggesting that the scratches were not the product of water action. Another difficulty was the presence of sediment deposits that did not

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