into the Earth. Pangaea's break-up placed the entire region under stress until the crust broke and the giant door slowly opened over several million years. The door opened along the Eastern Border Fault, the major fault that forms the present eastern boundary of the Central Valley, and had a hinge near the Connecticut-New York line.

As the door opened, a long trench formed that shallowed westward toward the hinge-line. The Earth, in its constant search for equilibrium, tried to fill up the growing trench - from above and below. From above came sediments washed off the towering Appalachians. From below came lava. For millions of years, layer after layer of sediment along with occasional outpourings of lava were laid down in the sinking valley, creating a vast wedge of brownstone and traprock. The more the door opened, the more the trench filled up. The wedge eventually attained a thickness of about two miles along the Eastern Border Fault, thinned westward, and stretched across the present Western Uplands at least as far as the Pomperaug Valley.

The sedimentary rocks in the wedge have given geologists a fair idea of what Connecticut's climate was like in Mesozoic times. Sediments are always deposited at the surface (although geologic forces may later bury them deeply) and, while they are at the surface, climate has an opportunity to make an imprint in this impressionable material. By studying brownstone carefully, geologists have worked out a surprising amount about the climate from subtle clues it left in the rock. Much of what is known comes from the excellent work of Paul Krynine, a Yale University geologist during the 1930s and 1940s. Krynine started with the most basic observation: brownstone is brown to red-brown. (Around New Haven, where the rock is especially red, the Central Valley's sediments are often called "red-beds ' ") Brownstone in turn has imparted its reddish color to the soils in the Central Valley. New Englanders have long pondered the Central Valley's red soils, so unusual for a northern climate. Worldwide, red soils are quite common - perhaps the most common soil color - but they are characteristic of tropical and subtropical environments and not temperate regions. Because of its underlying brownstone, the Central Valley has the soil color of Jamaica. Krynine took this observation, added a couple hundred million years to it, and

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