42 



The distribution of the water-worn fragments of opalized 

 woods already referred to, bearing testimony directly upon 

 the age and extent of this old lake basin and its eiffluents, is 

 of considerable importance. The only link wanting appears 

 to be the relative age or position of these trees with respect 

 to the various distinctive beds within the Tamar Valley. 



In a cutting of the Launceston and Western Railway 

 beyond Breadalbane a section of tufaceous basalt is exposed. 

 Embedded in some cases in the softer, but more frequently in 

 the harder, rock are numerous trunks and branches of fos- 

 silized trees, generally disposed horizontally. The difference 

 between these remains and the silicified fragments so abun- 

 dant in the gravelly beds is as follows : — 



They are chiefly composed of lime, and consequently, while 

 the harder parts of the structure appear more boldly in relief, 

 the fine cellular structure, so common to the silicified speci- 

 mens, is scarcely discernible. The thickness of these is gene- 

 rally from two to three feet, and the trees appear to have 

 been very resinous. The centre from which the medullary 

 rays spread is generally one mass of amber-like matter, and 

 when it has been exposed for any length of time to the atmo- 

 sphere, it assumes a white, twisted, asbestos-like appearance. 



FOSSIL FEUIT. 



Intimately associated with these trees I discovered a cluster 

 of fruits, also preserved in lime. 



They are small, egg-shaped nuts, grooved longitudinally, — 

 length, |-inch ; breadth, ^-mch..—(See Fig. 27.) 



If any of the trees here referred to could be identified with 

 the silicified fragments scattered throughout the upland 

 plains, we would be enabled to indicate the position of the 

 latter with respect to the Launceston beds, as the enveloping 

 basalts and tuffs immediately overlie the bed of lignite at the 

 Railway " Big Cutting," near to the Fossil Tree Cutting 

 already referred to.* 



The bed of lignite at this point, although it has not been 

 penetrated, has been ascertained to be of considerable thick- 

 ness. It is for the most part very impure, and is thickly 

 studded with small beads of resin, which on ignition flame 

 briskly. 



Compressed branches and stems {^ig. 25) occur in great 



* Since writing the above, I have been aided by I\Ir. E. D. Harrop, of the 

 Commercial Bank, Launceston, in making microscopic examinations of the 

 various fossilized trees found either as trunks in situ, or in the form of water- 

 worn pebbles ; and while we consider that there is an indication of different 

 vaiieties, yet all such remains are evidently coniferous. This also applies to 

 those preserved in a ferruginous form. It is veiy remarkable, considering 

 the greater abundance of leaf remains of other trees, that only coniferous 

 woods are preserved to us in the maimer already described. 



