Furthermore, owing to the weathering to which the adjacent rocks are subjected, material of the finer sort, susceptible of transportation by rains and ordinary floods, is more abundant during the meadow period than during the lake period.

此外，由于邻近岩石受到风化作用，更细的物质，容易被雨水和普通洪水输送，在草甸时期比在湖泊时期更丰富。