Opal phytoliths in some Victorian soils and "red rain" residues

Abstract

Opaline bodies in certain Victorian soils have been regarded in the past as sponge spicules. It is now shown that the majority of these opaline bodies are the same as those developed in certain plants, hence they are recorded as opal phytoliths. This corrected identification of the opaline bodies is of fundamental significance in affecting certain aspects of the interpretation of the history of such components of soils. It is no longer necessary to consider these bodies of opal as sponge spicules carried into soils by wind transportation or other means. They are released from plants containing them and shed into the soils on the decomposition, or destruction during grass and forest fires, of phytolith-bearing vegetation, or sometimes via the dung of graminiferous animals. A few smaller phytoliths do become wind-borne, as evidenced by their occurrence in "red rain" and "red snow" residues. It is also shown that distilled water should always be used in treating soils for examination of their phytolith populations, because a small quantity of the smaller phytoliths (and diatoms) occurs in tap-water.