Bairnsdale Gravels and Fossil Wood. 171 



4. — The unconformable relation of this gravel bed to the under- 

 lying shallow marine deposits, and its aspect in regard to the 

 present physiography of the coast allow of no other conclusion than 

 that it is terrestrial. 



Age of the Fossil Wood. 



(a) Evidence for Kalimnnn Age. 



Although the gravels containing the logs and p(|bbles of silici- 

 fed wood havi been shown to be of Werrikooian age, the timber, 

 te'ng already mineralised, must have had an earlier origin. It 

 has been previously noted that some of the Kalimnan shallow marine 

 beds are replaced in certain areas by fine silioious sands, and it i& 

 reasonable to assume that there, by their freedom from marine 

 fossils, they were parts ot old land surfaces. It is probable that 

 upon these Kalimnan sands g)-ew the tall timber which gave rise to 

 the silicified tree stems. As these old pioneers of our present 

 heritage of the Gippsland forests arrived at maturity, they would 

 in the course of events succumb to the fury of wind and rain and 

 become buried in silt and sand. Through the percolation of alka- 

 line water they would readily yield to silicification, much in the 

 same way as the Acao'as and other trees and shrubs of the Cairo 

 petrified forests were formed. 



That these trees did not grow in any profusion on the slopes of 

 the northern ranges is an inevitable conclusion, seeing that at 

 that time, as now, there must have been a great deal of vertical 

 erosion on the sides of the hills, and that the natural home for the 

 forests would be along the foothills and flats. There the accumu- 

 lated remains of logs and branches would be gathered, where 

 quieter conditions of deposition would obtain, inducing fairly 

 rapid silicification. The same forces which would break up the sur- 

 face of the older beds to form the Werrikooian gravels would also 

 bring down the fragments of volcanic rocks and quartzites from' 

 the high lands to the north, 



(b) Evidence for Janjjilxian Age. 



On the other hand it might even be proved by the collection of 

 further evidence from stratigi-aphical relationship, that the silici- 

 fied wood was derived from quartzitic deposits under the older 

 (Miocene) basalt-lavas, of which there are numerous remnants along 

 the upper reaches of the Dargo, and Tambo Rivers. This could 



