Gravel, on the other hand, is like a melting pot of a lot of different rock pieces, including limestone, basalt, and sandstone. Put simply, limestone is a type of rock that is formed by organisms ...

For most organisms on Earth, rocks are objects, not food. But for one oddball microbe, desert limestone seems to have been on ...

Chalk, limestone, shale ... some of the minerals in the sediment harden and form a kind of cement which sticks the grains of the rock together. Look through the slideshow to find out more about ...

These sediments become compacted to form a new type of rock called sedimentary ... the Marble Arch Caves are situated in a limestone area. Limestone is a sedimentary rock made up of bits of ...

Mysterious tunnels in desert rocks may be the work of unknown microbes, hinting at a hidden world inside marble and limestone ...

In the desert areas of Namibia, Oman, and Saudi Arabia, research work has revealed unusual structures that are probably due to the activity of an unknown microbiological life form. Unusually small ...

Unusually small burrows, i.e., tiny tubes that run through the rock in a parallel arrangement from top to bottom, were discovered in marble and limestone ... of this kind in the Namibian desert ...