Australia: The Land Where Time Began

A biography of the Australian continent 

Walloon Coal Measures

According to the authors¹ the Walloon Coal Measures, a series of volcanolithic sandstones, coal, mudstones and siltstones with a maximum thickness of about 250 m, extending over wide areas of the Surat Basin and the Clarence-Moreton Basin in southeastern Queensland are the most notable of several units in which terrestrial fossils of Middle Jurassic age have been found. Fossils in this deposit have been collected from road cuttings and underground coal mines. Plant macrofossils and spore/pollen assemblages have been used to date the deposit to the Bathonian to Callovian. The deposits originated with southward-draining river systems, by a combination of major channel, flood basin and peat swamps in which coal formed.

In Australia the high palaeolatitude macrofloras of Bajocian-Bathonian, Middle Jurassic, are well known from the Walloon Coal Measures, representing communities of a humid swamp. Preserved in these deposits is evidence of the rich understorey that grew in the area in the Middle Jurassic. Among these understorey plants were osmundacean, dicksoniacean and dipteridacean ferns, liverworts, lycophytes, equicetaleans, Taeniopteris, a pentoxylacean, a genus that continued through to the Cretaceous and bennettitaleans, primitive plants that were cycad-like. The main canopy elements were conifers, the araucarian, Podozamites, and the podocarp, Elatocladus, seasonality is suggested by the well-defined growth rings in the preserved trunks of these conifers. There doesn't appear to have been many, is any, times of drought, as suggested by the extensive accumulations of peat

Sources & Further reading

1. Kear, B.P. & Hamilton-Bruce, R.J., 2011, Dinosaurs in Australia, Mesozoic life from the southern continent, CSIRO Publishing.