10,000 YEARS OF DESERT LOESS + 90 YEARS OF DESERT LOESS INVESTIGATION

Obruchev wrote about loess in North Africa in 1914- perhaps the first reference to loess in the Saharan region. Obruchev appears to have initiated the idea of a specifically 'desert' loess- the concept has been around for about 90 years. In 1954 B.Butler, in Australia, suggested that desert loess was a chimera- it did not exist. He said this after failing to find classic loess in Australia- a notoriously desertic continent. It appeared, on examination of the world's large hot deserts, that the Sahara and Australian deserts were short of associated loess,but the Central Asian and North Chinese deserts had an abundance. A question began to be asked: if there is loess at desert fringes, how are the particles made? where in the desert is there a good source of quartz silt to form the deposits? 'Making the material' became the test for desert loess, and many mechanisms (some just about believeable) were proposed. Now it seems that 'in-desert' mechanisms are not needed. Loess material does come out of deserts; but first it goes in. Deserts are storage places, reservoirs for loess dust- which is made elsewhere. It is notable that the two great loess deserts are next to High Asia- that focus of geo-energy which is perhaps the Earth's greatest consistent silt provider. The Chines and Central Asian loess, having passed through deserts, is mountain loess; it comes from High Asia. Recently Sun Jimin has produced evidence that this is the case.