Akt. XII. — A Physical Description of the Island of 



Tasmania. 



By the Rev. J. E. Tenison- Woods, F.G.S., F.L.S., Hon. 

 Mem. Roy. Soc. N.S.W., Tasmania; Cor. Mem. Roy. 

 Soc. Vict.; Vice-Pres. Linn^ean Soc. N.S.W., &c, &c, 



[Contributed 10th August, 1882.] 



THe island of Tasmania lies off the south-east extremity of the 

 continent of Australia. It is separated from it by straits 

 about 150 miles wide, and lies between lat. 43° 39' and 40° 

 44' S., and long. 144° 38' and 148° 24' E. It is somewhat 

 wedge-shaped, the narrow end being towards the south, as in 

 most islands and continents. Its area is estimated at about 

 27,000 square miles. Its contour is extremely diversified 

 with numbers of deep indentations, estuaries, and bays, 

 which give it a coast line of very great extent, far superior 

 to any equal area in Australia. It may almost be described 

 as a cluster of high mountains, with a large lake area on its 

 tablelands, and a very extensive drainage or river system. 



Tasmania is generally considered as a detached portion of 

 the great Australian Cordillera, or mountain system of the 

 eastern side of the continent, which extends from Wilson's 

 Promontory right up to Cape York, in Torres Straits. 

 Tasmania is nearly in the same line south of this mountain 

 range, and is more or less connected by long islands lying in 

 the same direction and a chain of rocks. But this unity of 

 direction would not of itself prove them to belong to the 

 same mountain system. The two separated portions should 

 belong to the same geological formations, and owe their 

 elevations to the same forces. That this is the case is 

 capable of demonstration. 



The great Australian Cordillera may be described as a 

 mountain system composed of certain definite formations, 

 which are more or less well represented in the whole of its 

 course. There is first a granitic axis, on the sides of which 

 altered rocks, schists, slates, and gneissose rocks of uncertain 

 age are seen to rest. Above these are rocks belonging to the 

 Cambrian, Siluro-Cambrian, and Silurian systems, on which 

 are found quartz veins with gold and other minerals. The 

 stratified rocks of this system are always much folded and 



