34 NOTES ON THE GEOLOGY OF MAKIA ISLAND, 



is a fine beach here ending in a long sandj^ hook. In 

 northerly and southerly weather an ugly sea gets up 

 quickly owing to the shallowness of the water. 



Maria Island is one of those curious "tied-islands" to be 

 found in Tasmania. The reason for their formation has 

 not yet been determined, though it is usual to ascribe 

 it to the sinking of the land, and, though not sufficient 

 data has been collected to dogmatics on the matter, there 

 is no reason to suppose that there have been any other 

 forces in operation. It is interesting to note that at the 

 present time the shore is sinking both in Shoal Bay and 

 also at Orford, on the opposite side of the passage. The 

 same thing is taking place near the mouth of the Huon 

 at Garden Island Creek, and at Kelly's Basin, Port Davey. 

 The isthmus is narrow, low-lying, and sandy, and scarcely 

 raised above sea-level. Shoal Bay is very shallow, though, 

 there is a deep channel off its fjouth-western extremity. At 

 the head of the bay is a beach, the sand of which is 

 largely composed of shell-fragments. Riedle Bay is much 

 deeper, and well scoured by the south-easterly gales. Its 

 beach is composed almost entirely of cpiartz grains trom 

 the granites that fringe its shores. The most prominent 

 feature of the North Island is the great central mass of 

 Mt. Maria and the Bishop and the Clerk, the highest 

 point of which is about 3,000 feet high, and from which 

 the land slopes, in parts precipitously, in parts gently, 

 down to the sea. High hills also cover the South Island, 

 which is smaller and not so elevated. The coast line is 

 most irregular with high cliffs on the north, south, and 

 east, and low-lying rocks to the west, interspersed with 

 fine white beaches. 



The densest vegetation is to be found on the slopes 

 of Mt. Maria, especially on the east where it intercepts 

 the breezes from the sea. Here the Oyster Bay pine is 

 a prominent feature. The rest of the island is well- 

 wooded with eucalypts and she-oaks, though thinning out 

 on the poorer soils of the granite areas. 



The geology of the east is quite distinct from that of 

 the west. The rocks on the western half of the island 

 are almost entirely made up of Mesozoic sandstone and dia- 

 base of the usual type, while on the east Penno-Oarbonifer- 

 OU9 mudstones and conglomerates are interspersed with De- 

 voniau granites and older quartzites. The south-western 

 end of the island. Cape Peron, ends in a magnificent pillar 

 and axchway of diabase, from which it runs back to a 

 pyramidal peak above. The diabase continues in a north- 

 easterly direction as a steejily-sloping and precipitous 

 hill-side for about a mile where it junctions with the 



