to reach there the level 16 feet below pure iron culture. If we assume that these 19 feet of sediments began to grow contemporaneously with the founding of the kurgan, the relative rates of growth would be 52 : 19 = I :2.733. It is possible, however, that the whole thickness of the 7 feet of submerged culture-strata contributed to the layer of "wash" with pottery in shafts E and F; therefore, if we subtract these lowest 7 feet of culture-strata, shown in shaft D, from the 52 feet in the main body of the kurgan, we have the rates : 45:19=1: 2.368, say 2.37. But, everything considered, it would seem proper to take I to 2.5, i. e., I of natural
Fig. I0.—Section of a Wall in the North Kurgan.
sediments to 2.5 of culture-strata, as the relative rates of growth in connection with the closely compacted culture-strata of the three older periods. This ratio being obtained from the parallel accumulations of a considerable period of time has, as we shall see later, for our purpose both an archeological and a geological value.
After the sediments had reached the height shown in shaft D, there came a change, and this part of the plain was dissected, for a little farther eastward, in shaft B, we find a new series of sediments marking a renewed aggrading. Now when this new growth had reached the level indicated on the section by an arrow in shaft B, it received fragments of the pottery peculiarly characteristic of the
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