The integrative units described in the preceding section are well adapted to express the extraordinarily complex and fluid relationships of archaeological phases over wide geographical areas, but they cannot furnish the rigid spatial-temporal frames that archaeologists seem to find so reassuring. For these we generally turn to some system of matching phases from region to region, expressing the results by means of a diagram in which the regional sequences are arranged in parallel columns with their phases stacked up like boxes, scaled against a real or imaginary vertical time band at one side. Illustrations are available in current archaeological literature in great profusion and variety. The appearance of an archaeological report without such a diagram would in fact be something of a curiosity today. This is what Rouse, in the paper already cited, has called "distributional correlation of phases," and the resulting diagram, of which he presents an excellent model,1 is often referred to as an "area chronology."
We have expressed agreement with Rouse that so far as possible such a scheme should be effected by means of independent, extracultural cross-dating, e.g., radiocarbon dating, dendrochronology, river-channel and river-terrace sequences, discrete geological and meteorological events (volcanic eruptions, droughts, etc.)--in short, any available techniques of dating that do not involve assumptions about culture. Unfortunately, in the present stage of____________________