32 



THE GEOLOGIST. 



dually increasing in thickness until a cliff is exposed some 50 to 80 feet 

 high, formed of the first-mentioned beds above, and the latter lying in con- 

 formable stratification at the base. 



These latter beds are somewhat remarkable near this place (Pic-nic 

 Point) for being filled with a vast number of tubular- shaped bodies, covered 

 on the outside with warty excrescences. These tubes vary in size from 

 the thickness of a straw to that of a man's wrist. Within them there is 

 generally found a core, easily removable by a little gentle pressure. The 

 outside of the tubes in question being harder than the other portions of 

 the strata, they, of course, resist the action of the waves more successfully, 

 and stand out from the containing matrix in singularly bold relief; often, 

 when half imbedded, reminding one of some huge chiton clinging, for bare 

 life, to his stony habitat, upon which he has been left high and dry by the 

 receding tide. Although bearing a very strong resemblance to fossils, the 

 appearances witnessed are generally regarded by local geologists as due 

 to the decomposition of hematite, with which the same kind of rock is 

 known to abound. 



The upper beds in this particular spot, represented by a soft arenaceous 

 stone, do not appear to be fossiliferous,butalso contain certain tubular bodies 

 ■ — very different, however, from those last mentioned — generally traceable 

 for many inches at a time, and of a chalky appearance, Having for- 

 warded a small hand-specimen to the Kev. j. E. Yv r oods, of Penola, that 

 gentleman suggested they might be a species of fulgurite due to the ac- 

 tion of lightning, — a theory which seemed to be especially favoured by 

 the tubes being invariably found in the higher portions of the strata, and 

 nowhere traceable at a few feet from the surface. Subsequent observation 

 has, however, would seem to show that these appearances must be referred 

 to a far less romantic origin than " the fire of Jove ; " in fact, on exami- 

 ning them more closely, many appeared to be filled with a black and 

 crumbling substance resembling decayed vegetable matter, and on search- 

 ing still further, I discovered one in which a piece of wood, evidently the 

 root of a shrub or tree, was still contained. Since then I have met with 

 similar specimens in Melbourne among some Tertiary rocks near the gaol, 

 and also at ISTortheote, where a thin capping of newer Pliocene deposits 

 rests on the Silurian strata. In this latter instance I observed many re- 

 cent roots, running downward into the loose rock almost perpendicularly, 

 around which the sand and fine gravel appeared to be invariably hardened 

 into a cemented pipe-like mass. Having tested these tubes with muriatic 

 acid, I should not expect them to contain lime, as I once supposed. 

 More probably, the potash in the wood combining with the surrounding 

 quartzose sand, has given rise — first to a solution, and afterwards to a de- 

 position of siliceous particles. 



Much of this district, near Brighton, is covered on the surface by depo- 

 sits of shells several inches in thickness, wherein Cardium, Turbo, Trochus, 

 Haliotis, and other species having representatives in the adjacent sea, are 

 found in great abundance. In some places, these shelly deposits, being 

 mixed up with arenaceous matter and small pebbles, by afterwards par- 

 tially decomposing form a soft, easily broken, shelly gravel or conglome- 

 rate, interesting to the young geologist, since he can thus readily trace 

 every step of the process which changes the loose sand, unconsolidated 

 pebbles, and aggregated shells, into a tolerably firm and stony rock of 

 highly fossiliferous character. 



The evidence of these shell-beds goes far to show the very recent up- 

 heaval of the surrounding district. A little observation will, however, 

 reveal traces of more than one phenomenon of this description, together 



