For a short period, soil formed and a tropical forest grew up.

All the time, for nearly 200 million years, soil was forming and being washed away.

The soil in that part of the state forms the Loess Hills.

Here soil hadn't collected and formed as it had in the Tiber valley system.

A thin, poorly developed soil, or regolith, formed over the paleotopographic high areas between the channels.

Soil biomantles, and soils, have been forming from the time that life began inhabiting land.

The primary conditions for soil development are controlled by the chemical composition of the rock that the soil will eventually be forming on.

But the storm continued, and the reddish-brown soil was forming pools of water.

There are some, and these probably ancient, where a deep soil has formed and the most valuable fruit-trees prosper.

Subsequently over the centuries, a thin but rich soil has formed.