We have considered the Laurentian highland and the glaciation which centered there. Let us now turn to another highland only the northern part of which was glaciated. The Appalachian highland, the second great division of North America, consists of three parallel bands which extend southwestward from Newfoundland and the St. Lawrence River to Georgia and Alabama. The eastern and most important band consists of hills and mountains of ancient crystalline rocks, somewhat resembling those of the Laurentian highland but by no means so old. West of this comes a broad valley eroded for the most part in the softer portions of a highly folded series of sedimentary rocks which are of great age but younger than the crystalline rocks to the east. The third band is the Alleghany plateau, composed of almost horizontal rocks which lie so high and have been so deeply dissected that they are often called mountains. The three Appalachian bands by no means preserve a uniform character throughout their entire length. The eastern crystalline band has its chief development in the northeast. There it comprises the whole of New England and a large part of the maritime provinces of Canada as well as Newfoundland. Its broad development in New England causes that region to be one of the most clearly defined natural units of the United States. Ancient igneous rocks such as granite lie intricately mingled with old and highly metamorphosed sediments. Since some of the rocks are hard and others soft and since all have been exposed to extremely long erosion, the topography of New England consists typically of irregular masses of rounded hills free from precipices. Here and there hard masses of unusually resistant rock stand up as isolated rounded heights, like Mount Katahdin in Maine. They are known as "monadnocks" from the mountain of that name in southern New Hampshire. In other places larger and more irregular masses of hard rock form mountain groups like the White Mountains, the Green Mountains, and the Berkshires, each of which is merely a great series of monadnocks.