China, and Japan. All the evidence thus implies for early Pliocene times an equable and uniform climate, which permitted the intimate association in our continent of many plants which are now no longer able to exist at similar elevations or in one and the same latitude.
The mammalian life of Europe in early Pliocene times was in keeping with the flora. The deinotherium and mastodon still survived, and along with these were rhinoceroses, hippopotamuses, and elephants, and many cervine and bovine animals. Carnivores of extinct and still existing types and many monkeys were also present.
Such, then, was the character of the climate, and the aspect of the flora and fauna of Europe in preglacial times. The gradual approach of glacial conditions is evidenced by the fact that the percentage of northern and arctic shells in the upper Pliocene marine deposits increases from the lower to the higher members of the series. We note a gradual dying out of southern species and a gradual coming in of northern forms, until at last the beds are charged with the remains of a truly arctic marine fauna. We have no direct evidence as to the terrestrial conditions which obtained in Britain and Ireland at that time. The climate, however, could not have been genial and temperate as it is now. The presence of an arctic fauna in our seas shows that our shores were washed by currents coming from the north, and not as at present from the southwest. Reasoning from the analogy of to-day, therefore, we might infer that the climate of our area was probably not unlike that of Labrador.
The traces of the first glacial epoch are more clearly read in the deposits of the continent. An immense glacier at this time, fed from the uplands of Scandinavia, filled the basin of the Baltic. The bottom moraine of that great ice flow is seen in the low grounds of Scania, in southern Sweden, while its fluvio-glacial deposits have been detected at many places in north Germany. The alpine lands were contemporaneously covered with extensive snow fields, and large glaciers descended the deep mountain valleys, to deploy upon the Vorländer, in Switzerland, and south Germany. The terminal moraines of these glaciers have been mapped out, and the general conditions of the epoch have been so well ascertained that the position of the snow line at the time has been determined. It is believed to have been upon an average some 4,000 feet lower than now. While the valleys of the Alps were thus gorged with ice and the basin of the Baltic was occupied by an immense mer de glace, it is not probable that the higher parts of our islands could have escaped glaciation. We can hardly doubt that snow fields and glaciers must also have existed here. No trace of these, however, has been or is ever likely to be detected. Direct evidence of the kind, if it ever did obtain, has been obscured or destroyed by the action of the much greater glaciers and ice flows of later epochs.
In tracing the succeeding events in the geological history of Europe,
