The life of these Indians continued unchanged in any of its major features until perhaps 2000 or 1500 B. C. About that time, according to radiocarbon dating, the knowledge of pottery making seems to have reached them in some manner which has not yet been determined. Perhaps they even discovered it for themselves; but it seems more probable that the idea reached them from some fairly distant tribe, and that by local experiment they developed their own techniques from a hazy understanding of the principles involved. At any rate, the upper levels of the older shell mounds begin to yield “sherds” (fragments) of a coarse undecorated pottery which contains innumerable tiny holes running through the paste in all directions. These are the channels which remain after some vegetable material like grass or moss fibers was burned out when the vessel was fired. Any substance mixed with the clay to make it easier to handle and keep it from cracking during the drying out and final firing of the pot is known as “temper,” and the process itself is called “tempering.” Later potters learned that a temper of sand, crushed shell, or, better still, crushed rock or crumbled bits of old pottery made stronger and better pottery; and therefore “fiber-tempered” wares usually represent the oldest type of pottery we find in any region where they occur. While this pottery was undecorated at first, its makers in the Georgia area later developed a type of decoration composed most often of lines of indentations, or punctates, made with the point of a stick or a bone tool. [Illustration: Except for caves, a rough windbreak to give protection from bad weather was probably the only shelter known to the earliest Indians.] This new item in the household inventory was probably one of the most significant advances which ever took place in the life of the American Indian, and second in importance only to the later introduction of agriculture. With it, the awkward and tedious routine of stone boiling came to an end, and soups and stews enlarged the menu and became at once the easiest prepared and one of the most appetizing of the foods used. Pottery, too, marks a big change in the work of the archeologist when it appears in the cultures which he is studying. Types of projectile points and other stone artifacts have a way of continuing in use for long periods without change. Clay vessels, however, seem to have been constantly changing in form or decoration or construction, possibly because the potter’s clay is so plastic and responsive to any fancy it is desired to express, and there are many different ways of producing similar results. For this reason, it forms a sensitive indicator of the passage of time and is one of our best clues to relationships between sites and the cultures of their inhabitants.