390 Transactions. — Geology. 



argillaceous, and frequently feldspathic, the latter passing into- 

 greywacke. They are mostly hard, being seldom soft, except 

 where crushed, much jointed and shattered. Veins of quartz 

 are common in the sandstones, especially in the yellowish- 

 green variety. 



The shales and claystones are present in endless variety, 

 ranging in colour from pale-grey to yellowish-grey and green, 

 from dark-green to black, and from chocolate-colour to red 

 and purple. They are argillaceous and occasionally siliceous, 

 but, like the sandstones, rarely calcareous. They are gene- 

 rally much jointed, and, when interlaminated with bands of 

 the harder and more unyielding sandstone, are often crushed 

 into a crumbling and drossy material presenting shining and 

 slickensided surfaces, which led Sir Julius von Haast to de- 

 scribe them as " serpentinous." Some thin bands of slaty 

 shale are silky in lustre and quite fissile. 



These rocks dip at high angles in one continuous succes- 

 sion of beds to the north-west, thereby exposing between 

 Mount Potts and Mount Goethe a thickness of not less 

 than 40,000 ft. of strata. 



The strike of the strata, from Rocky Gully to the junction 

 of the Clyde and Lawrence Rivers, and thence up the Clyde 

 for a mile and a half, is uniformly N.E.-S.W., and the dip 

 N.W. The angle of dip varies from 65° to 70° at Rocky 

 Gully to 83° at the river-junction, and in the Clyde for the 

 first two miles from 85° to nearly vertical. 



The strike, about a mile and a half above the junction, 

 trends more towards the north, gradually bending from N.E. 

 to N.N.E. until it is about N.-S. two miles above the Law- 

 rence. From Maiden Flat Creek to Mount Goethe the strike 

 IS N.N.E.-S.S.W., and the dip W.N.W. at angles varying 

 from 55° to 85°, the flatter angle being observed near Maiden 

 Flat Creek. 



The most careful search failed to discover organic remains 

 in this magnificent pile of clastic rocks, excepting some 

 obscure markings in the bands of black silky slate, which 

 might be referred to annelid trails. No less remarkable than 

 the absence of organic remains was the absence of limestones 

 or calcareous beds, a circumstance commented upon by Sir 

 Julius von Haast, who examined the same rocks in the 

 Rakaia Valley and neighbourhood of Mount Cook. 



The Jurassic and Triassic formations of New Zealand are 

 everywhere connected in one continuous stratigraphical suc- 

 cession, and where the Upper Trias are fossiliferous, as at 

 Nugget Point and Nelson, it is not difficult to establish a limit 

 to the one and a beginning to the other. But in the Moimt 

 Potts section the Permian alone are fossiliferous, and it 

 becomes a matter of dilliculty to determine where the Trias 



