BY V. F. BROTHBUUS AND W. W. WATTS. 365 



Tertiary 'leads' of Kiandra, underlying the basalts, have yielded 

 fine collections of leaves. 



"Briefly, the history of Yarrangobilh^ appears to have been as 

 follows : — 



In Pre-Silurian times a great amount of volcanic ash was piled 

 upon a sinking sea-floor. As time progressed, the adjacent land 

 was elevated, and the waste from this was brought down by tor- 

 rential streams to form a great conglomerate along the shore-line. 

 As the mountains were reduced by denudation, the conglomerates 

 were overlain by sandstones, and these in turn by mudstones. 

 Long afterwards the sea-water became free from silt, and long 

 lines of coral reefs sprang into existence on the site of the old 

 mudstones. These corals and their associated alg?e and mollusc 

 growths then formed belts of limestones in which now occur the 

 Yarrangobilly Caves. 



Then came another change. This old sea-deposit sank still 

 lower in part, and in turn received other conglomerates, sand- 

 stones and limestones. This was the work of the Devonian 

 period. 



A mountain-making period turned the Devonian sea into high 

 dry land, and this has remained above sea-level ever since. 



During this period of mountain-making, many I'eefs of gold and 

 copper were formed, and as the streams wore the mountain-ranges 

 away, the gold-contents of the reefs were in part washed into 

 the watercourses. These rivers at a slightly later period became 

 almost lake-like in width, and many plants became buried in the 

 river-muds and were turned into fossils. The earth now became 

 ci'acked by great fissures, along and up which molten lava flowed 

 and buried the surrounding country. 



A short time since, geologically speaking (end of Tertiary 

 period), the Kiandra and Yarrangobilly district was a great plain 

 near sea-level. It was then lifted up about 4,500 feet. In the 

 process, many parts, failing to hold together, would fall down in 

 terrace-form from the highest block. Thus Kosciusko is the 

 highest step, while Cooma and Yarrangobilly are lower blocks of 

 this uplifted plain, which have fallen away from the highest one. 



