to take in the colors. Despite their popularity, some confusion exists over exactly where the Litchfield Hills begin and where they end. For many people, the entire Northwest Highlands region (and a good bit of the Southwest Hills, too) is the Litchfield Hills. Although it is perhaps not as dry a term as "Northwest Highlands," such a broad use of the name "Litchfield Hills" voids it of meaning. But if we take the Litchfield Hills truly to be the foothills of the Berkshires, then the physical extension of the Berkshire Mountains into Connecticut is the most sensible Delia-- tion - that is what is meant here by "Litchfield Hills . "

In addition to the Taconic and Litchfield Hills plateaus, the Northwest Highlands also contain the Hudson Highlands Plateau and the Housatonic Highlands Plateau. All the plateaus exist because their bedrock cores are much more resistant to erosion than the bedrock of the valleys below. The plateaus consist of tough schists and granites, similar to rocks found elsewhere in the Eastern Uplands and Western Uplands. But the valleys are sunk into marble. Although marble is a metamorphic rock like schist and gneiss, it is not (in our climate) resistant to erosion. The weak character of marble stems from its parentage. Marble is derived from the metamorphism of limestone, a sedimentary rock composed mostly of carbonate mud and the shell fragments of marine fossils. The lime-rich minerals that make up shells and carbonate mud weather quite easily. (Seashells left outside rapidly take on a dulled appearance for the same reason.) Thus, marble is readily dissolved by the slight acidity of natural rainwater, and the rains of eons have eroded wide, deep lowlands between the high plateaus of the Northwest Highlands.

The marble lowlands of the Northwest Highlands are often lumped together and called the Marble Valley. The Housatonic River for most of its run through Connecticut to Long Island Sound follows the Marble Valley, taking advantage of the ease with which Connecticut's marble is eroded. Actually, the term Marble Valley is somewhat misleading because there are really two Marble Valleys, a northern and a southern, which do not connect with each other. The Housatonic River follows the northern Marble Valley as far south as the Housatonic Highlands plateau, two miles south of Falls Village. There, the river leaves the marble to take a much tougher but shorter route through the Housa-

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