These locks are thick pile in the form of a bread oven, made of piled on each other kus Cove wood and twigs, deprived of the cortex, as well as earth, clay and sand, saying that inside, except for residential premises, there is storage for food stocks. If the level in the hole in the river or stream varies considerably during the year or if the stream does not have the desired depth, the Beavers hold on C / O currents are high and, depending on the speed of flow, thick dam increase the level of the water and arrange themselves so above the dam open water swimming. Not many years ago, Morgan studied for more than 50 such dams in the primeval forests on the shores of Lake Superior in North America, photographed and described in detail with them in the subordination of the beaver and its buildings. Some of these dams reach 150-200 feet in length, 2.3 meters in width, thickness at the base of 4-6 meters, and at the tip of only 1-2 meters. They consist of poles thick as an arm or leg, the length of 1-2 meters, which at one end driven into the ground, while others come to the surface water are interconnected by thinner bars, and the intervals between them filled with reeds, mud and earth, so that from the current forms by nearly plumb a wall, and on the opposite side Ny – skat. Beavers do not always hold the dam in a straight line across the flow and just do not always arrange it so that it is in the middle had the appearance of the speaker angle, often carried out in the water in the form of an arc with convexity against the flow of.