The dams, too, were drilled by water-rats, and the streams percolating through, slowly increased the size of these tunnels till the structure burst, and the current swept on and added to the floods below.

Mill-dams stood longer, but, as the ponds silted up, the current flowed round and even through the mill-houses, which, going by degrees to ruin, were in some cases undermined till they fell.
Everywhere the lower lands adjacent to the streams had become marshes, some of them extending for miles in a winding line, and occasionally spreading out to a mile in breadth.

This was particularly the case where brooks and streams of some volume joined the rivers, which were also blocked and obstructed in their turn, and the two, overflowing, covered the country around; for the rivers brought down trees and branches, timbers floated from the shore, and all kinds of similar materials, which grounded in the shallows or caught against snags, and formed huge piles where there had been weirs.
Sometimes, after great rains, these piles swept away the timbers of the weir, driven by the irresistible power of the water, and then in its course the flood, carrying the balks before it like battering rams, cracked and split the bridges of solid stone which the ancients had built.

These and the iron bridges likewise were overthrown, and presently quite disappeared, for the very foundations were covered with the sand and gravel silted up.
Thus, too, the sites of many villages and towns that anciently existed along the rivers, or on the lower lands adjoining, were concealed by the water and the mud it brought with it.

The sedges and reeds that arose completed the work and left nothing visible, so that the mighty buildings of olden days were by these means utterly buried.