In the desert areas of Namibia, Oman, and Saudi Arabia, research work has revealed unusual structures that are probably due ...

After roughly shaping a chunk of flint with a file, the marble-maker placed the piece on a basin of abrasive rock and hemmed it beneath a small waterfall in a creek. After weeks of turning ...

Marble is a metamorphic rock ... all of the processes by which the sediment is formed. For example, small pebbles of rock are rolled along a river-bed. 2 Deposition In deposition, sediment ...