GEOLOGY OF TASMANIA. 67 



Mary, on either side of Lovett, and the beach south of the 

 Regatta Ground, show these rocks in great variety. A good 

 deal of free gold has been shed into the alluvial flat at 

 Lymington. The source of the metal is believed to be the 

 line of contact between the porphyries and the Permo-Car- 

 boniferous sediments. This belt of rock passes S. to 

 the other side of the Huon River, and N. across to Oyster 

 Cove. 



Mesozoic. 



The series of freshwater beds which succeed to the Upper 

 Palaeozoic belongs to the Mesozoic division, but cannot, as 

 yet, be subdivided with certainty. The nearest approach 

 to a subdivision would be as follows ; but the reference to 

 European equivalents is quite provisional : — 

 Cretaceous (?) — 



4. Diabase (dolerite) in intrusive masses, laccolites, sills,, 

 and dykes. 

 Jura — 



3. Upper coal measure sandstones. 

 Trias — 



2. Sandstones and shales, with coal seams, at Ida Bay, 



containing Pecopteris lunensis (R. M. Johnston). 



1. Variegated sandstones, with Vertehraria australis 



(McCoy), and remains of heterocercal fishes and 



amphibians. 



1. The sandstones at the Government House Quarry, in 



the Domain, at Knocklofty, at Ross, &c., belong to the 



Lower Mesozoic. Mr. R. M. Johnston considers the Lower 



Sandy Bay mudstones, exposed three miles from Hobart, on 



the Brown's River Road, to be the base of the system. 



They contain obscure plant impressions. The variegated 



sandstones of Lower Sandy Bay are supposed to overlie 



them conformably. In the Domain, the sandstone has 



yielded bones of amphibians {Lahyrinthodonts V). From 



the Cascades to Knocklofty, there are about 1000 feet of 



these sandstones, from which the heterocercal fish, ^croZep'^s 



hamiltoni (Johnston and Morton), has been recorded. 



Messrs. Johnston and Morton give the section in ascending 



order, as follows : — 



Feet. 



1 . Yellow fissile sandstone 20 



2. Flaggy sandstone, with fish remains 5 



3. Mottled shales, with plants 60 



4. Thick sandstone beds, quarried for build- 



ing 715 



800 



