EVERYDAY SCIENCE

Detailed explanation-1: -Besides being distinctive, a volcanic-ash layer has four other advantages for purposes of correlation: it was laid down in an instant of geologic time; it settles out over tremendous areas; it permits physical correlation between contrasting sedimentary environments; and unaltered mineral crystals that…

Detailed explanation-2: -Volcanic ash is, obviously, an igneous rock: it comes out of volcanoes, and you can hardly get more igneous than that. As such, you might be surprised to find an article on volcanic ash dropped into a chapter which is otherwise about sediment and sedimentary rocks.

Detailed explanation-3: -Why are ancient volcanic ash deposits important to geologists? They form resistant rock layers containing fossils. They are easily dated using carbon-14. They serve as good geological time makers.

Detailed explanation-4: -Volcanic ash is also used as an abrasive in mechanics paste soap, abrasive hand soaps, and rubber erasers. Very fine ash is used in some toothpaste and powder, and minus-200-mesh ash has been used for polishing plate glass. Volcanic ash could be used instead of powdered pumice whenever the latter material is suitable.