been protected from complete dissolution by soil and subsoil flowing over and accumulating upon them, under the influence of thaw, in spring and summer. Such movements of superficial materials are indeed of common occurrence in high latitudes at the present day. The surface of the buried ice strata is very uneven, being furrowed and trenched by deep ruts and hollows. These depressions are filled up with frozen mud, etc., containing vegetable debris and abundant mammalian remains, including those of mammoth and woolly rhinoceros. Probably a large number of the bones may simply have been introduced into the hollows by the flowing soil in spring—they may have been lying originally scattered over the surface. In other cases, however, the animals themselves seem to have fallen or sunk into the depressions. All the evidence leads to the inference that in the warm season these high northern regions were visited abundantly by mammoths, rhinoceroses, horses, bisons, wapiti, and others. Such being the case, it is not hard to understand how the bulkier animals might now and again become trapped in the treacherous bogs and subjacent muds that covered and concealed the ice formations and their deep clefts and depressions.
When we turn to the loss of Europe, we meet with copious evidence to show that the wild animals of our prehistoric steppes and tundras were often done to death in their hundreds and thousands. Again and again great heaps and accumulations of their skulls and skeletal remains have been encountered in our lössic accumulations—appearances exactly recalling the similar bone finds of Siberia and North America. The deposits in which the European bone finds occur are of wind-blown origin, and we seem justified, therefore, in concluding that the animals perished in snowstorms. In these low latitudes, however, we could not expect to meet with ice formations like those of the tundras. But that drifted snows did formerly accumulate in middle Europe, and were preserved for long periods under coverings of sand and other materials, we have good reasons for believing. Indeed, even at the present day the drifted snows in southeast Russia are occasionally buried under sand and so persist for years. In one ease recorded by Borszcow, what appeared to be an ordinary sandhill proved to be a mass of congealed snow cloaked in sand about a foot in thickness. Immediately under the surface the snow was granular and neve-like, but a little deeper it was firm and solid like ice. This was in one of the tributary valleys of the Ilek, in the steppes south of Orenburg, about the fiftieth parallel—a relatively dry region. If in a low-lying region so far south snow can be preserved in this way, we may readily believe that in the steppe epoch of middle Europe snowdrifts similarly protected might now and again have persisted for years. But it was during the preceding tundra epoch that this would be most commonly the case. And much interesting evidence is forthcoming to show that in many places thick sheets of congealed snow did accumulate and become buried
