10 



The latter included blocks, huge, irregular, and tilted at 

 all angles, so as to obscure, if not conceal, the true lines of 

 bedding, are very puzzling ; but, if we accept a conclusion 

 which is forced upon us from independent considerations, we 

 can easily conceive how the otherwise regular lines of bedding 

 with the true sedimentary laminae may be harmonised with 

 the included angular blocks of a previous age. 



I have already observed that one of the limits of the base 

 of the formation was opposite Sandy Bay Point. There, on 

 the Brown's River road, a section exists, clearly showing the 

 older mudstone rock in situ, against which the upper 

 members of the tertiary lacustrine formation may be seen to 

 abut. (See Plate 2.) 



Now all who have travelled along the Huon Eoad, or who 

 have sailed under the cliffs at Bedlam Walls, must at times 

 have been struck with the regularity of the beds of the older 

 mudstone series as they lie over each other in vertical sec- 

 tions, and quarrymen at the new battery at Kangaroo Point 

 will tell you how easily one of the layers may be separated 

 from the adjoining one. Some of the layers, however, are 

 of softer texture than the rest, and consequently a wall of such 

 rock must wear away unequally. The rocky cliffs below the Shot 

 Tower are good illustrations of this unequal waste of certain 

 beds. At this spot there may be seen the rapid destruction 

 of a softer layer at the sea level, which, when far enough 

 advanced, will cause, as it has already done, the fall of 

 immense faces of the superincumbent mass, which, by 

 degrees will, by wind-driven waves of terrific force, be 

 strewed as angular blocks among the finer sands of the 

 advancing sea. 



Now, if we assume that the ancient tertiary lake here spoken 

 of had an extensive surface, of which, from other sources, 

 there are proofs almost amounting to demonstration, we 

 can readily conceive how the strewn angular blocks of 

 fossiliferous mudstone at a, fig. 1, came to be included among 

 the more regularly stratified clays and sands, and associated 

 with the fruit and leaf impressions of a later age. Nay, 

 more, the assumption thus forced upon us will enable the 

 observer, as it enabled me, to anticij^ate in great measure 

 what other observations in the neighbourhood can verify 

 and amplify. 



Let not the over-cautious, therefore, frown upon anticij)a- 

 tions of this kind, for in truth they are the half-lights or 

 the natural fruits of former observations, and when recog- 

 nised as such they constitute the more valuable part of that 

 inestimable possession which Professor Tyndall has happily 

 designated the " Scientific Use of the Imagination." From 

 this momentary digression let us again turn to our section as 



