Ice ages, such as the present one, are extremely rare. What seems likely is that ocean floors were higher in Cambra-Ordovician time, fluffed up by more than the usual amount of heat from the restless mantle-heat of the sort that has created the Hawaiian Islands in the middle of a lithospheric plate, and heat of the sort that lifts mid-ocean ridges, where plates diverge. Whatever the reason, the sea came up so far that it covered more than half of what is now the Nortl1 American craton. And after the white clean beaches and shelf sands had spread their broad veneer, lime muds began to accumulate in the epicratonic seas. The lime muds were the skeletons, the macerated shells, the calcareous hard parts of marine creatures. The material flexplek huren hilversum turned into limestone, and where conditions were appropriate the limestone, infiltrated by magnesium, became dolomite. As the deposit grew to a general thickness of two thousand feet, these Cambra-Ordovician carbonates buried ever deeper the sandstone below them and the Precambrian rock below that, pressing it all downward like tl1e hull of a loading ship, into the viscous mantle-but sedately, calmly, a few inches every thousand years. Absorbing the valley scene, the gapped and distant ridgeline, the newly plowed fields where arrowheads appear in the spring, I remarked that we had entered the dominion of tlrn Minsi, the northernmost band of the Lenape. They came into the region toward the dawn of Holocene time and lost claim to it in the beginnings of the Age of Washington. Like index fossils, they now represent this distinct historical stratum. Their home and prime hunting ground was the Minisink-over the mountain, beside the river, the country upstream from the gap. The name Delaware meant nothing to them. It flexplek huren rotterdam belonged to a family of English peers. The Lenape named the river for themselves. I knew some of this from my grade-school days, not many miles away. The Minisink is a world of corn shocks and islands and valley mists, of trout streams and bears, today. Especially in New Jersey, it has not been mistreated, and, with respect to the epoch of the Minsi, geologically it is the same. The Indians of the Minisink were good geologists. Their trails ran great distances, not only to other hunting parks and shell-mounded beach camps but also to their quarries. They set up camps at the quarries. They cooked in vessels made of soapstone, which they cut from the ground in what is now London Britain Township, Chester County, Pennsylvania.