BY W. H. CLEMES, B.A., B.SC. 35 



granite of Barren Head. This forms bold headlands and 

 rocky islands round the coast to Riedle Bay and Oape 

 Maurouard. It is generally massive in formation, but 

 varies in places and becomes highly jointed and, in con- 

 sequence, much hollowed by the waves, Sea Elephant or 

 Crayfish Bay being a notable example. As far as I could 

 judge the granite was of the usual type, though isome- 

 what coarser grained, in which orthoclase felspar predom- 

 inated, giving it a distinct reddish tinge. 



Riedle Bay is of surpassing interest to the geologist 

 as well as to the artisit and the lover of beauty in Nature. 

 The granites of Cape Maurouard are succeeded by Permo- 

 Carboniferous marine mudstones. These first appear as- 

 a narrow band lying horizontally on the low coastal cliff 

 of granite but rise later to a cliff, beautifully laminated, 

 fully 100 feet in height, extending for about a mile along 

 the shore and resting on a shelf of granite. Later the 

 mudstones disappear, the granite rises, up- to a cliff about 

 40 feet in height, on which is resting a narrow layer of 

 coarse p^ebbly conglomerate, of which mention will be 

 made later on. Then the granites give place to earlier 

 quartzites, which have been tilted up on edge and other- 

 wise deformed by the intruding granite. The highly 

 crystalline nature of this rock teatifies to the intensity of 

 the metamorpliO'sing action. With the limited time at my 

 disposal I wasi unable to collect sufficient material to' de- 

 termine the age of these rocks, and can only say that they 

 are earlier than the granite. The rocks in the same meri- 

 dional line to the north are given in the Geological Map of 

 Tasmania as Silurian, and there is no reason to suppose 

 that these are of an earlier horizon than that. They form 

 the outer edge of a well-sheltered corner, whose beach 

 continues over the isthmus to the northern side of the 

 bay. Here it is met by an immensie heaped-up pile of 

 boulders, mostly of diabase, an eloquent tribute to the 

 force of the southerly gales. The diabase is again succeed- 

 ed by a vei-y coarse-grained granite, on the top of whose 

 wave-worn srorface are stranded great diabase boulders, 

 which at first sight appear to have been hurled there by 

 the force of the waves, but later examination leads one to 

 suppose that they are either a talus from the high 

 diabase cap of Mt. Maria behind, or perhaps a small sill or 

 dyke sent from the same source. As we approach Boat 

 Harbour there appears to be another occurrence of the 

 quartzites which were found on the opposite side of the 

 bay. Here they are resting on the granites' but tilting 

 steeply southwards. These are sxicceeded by the gritty 

 basal beds of the Permo-Carboniferous series with its 



