He found at the bottom of the old Ballybetagh Lake, and resting on the true Boulder Clay (a product of the ice-sheet), a fine stiff clay which seems to have been brought in by the action of rain washing fine clay out of the Boulder Clay, that nearly covered the land, and depositing it in the lake. This action probably took place during a period of thaw, when the climate was damp, from the melting of so much ice, and the rainfall considerable. Then the climate improved, the cold of the Glacial period passed away, and the climate became warm. During this phase the next stratum was formed, consisting chiefly of vegetable remains. The summers must have been unusually warm, dry, and favourable to the growth of vegetation on the bed of the lake. About this time the Great Irish Deer appeared on the scene, for its remains were found resting on this layer, or stratum, in a brownish clay. This deposit also was the product of a time when the climate was mild. It is a true lake-sediment, with seams of clay and fine sand, the latter having been brought down by heavy rainfall from the hills, just as at the present day. Now, we have to consider how these Great Deer got buried in this deposit. How did they get drowned? They may have gone into the lakes to escape from wolves, or possibly to escape from ancient Britons (but that is still doubtful). Perhaps they went into the water to wallow, as is usual with deer, or they may have ventured to swim the lakes (see p. 19). To enter the lake from a sandy shore would be easy enough, but, on reaching the other side, they might find a soft mud instead, into which their small feet would sink; and the more they plunged and struggled, the worse became their plight, until at last, weary and exhausted, the heavy antlers pressed their heads down under the water, and they were drowned. It does not follow, according to this theory, that either the entire animal ought to be found, or even its legs, sticking in the clay. For a few days it might remain so, but the motion of the waters of the lake would sway the body to and fro, while the gases due to decomposition would render it buoyant, and perhaps raise it bodily off the bottom. Then it might float before the wind, its head hanging down, till it reached the lee-side of the lake. Then the antlers would get fastened in mud near the shore, thus mooring the body until at last so much of the flesh of the neck had decayed that the body got separated from it, leaving the head and antlers near the shore.