806 



GEOLOGICAL STJiUCTU HE. 



great angles, and dip outwardly from the iuterior 

 of the island, on its north and east side. 



Waier is likewise composed of the same beds, 

 but containing more conglomerate than those which 

 I saw on Maer, and for one balf its circumference, 

 has a regular quaquaversal dip from its centre, 

 but not at a greater angle than 10° or 15°. 



In none of the Murray Islands did I see any 

 traces of lava or igneous rock, except the fragments 

 contained in the conglomerates ; igneous rocks, 

 however, may exist in mass in the interior of the 

 islands, a fact which I greatly regretted that time 

 did not allow me to ascertain. 



In Erroob, on the contrary, the whole island is a 

 mass of igneous rock, from the summit to the sea- 

 shore, with the exception of a small portion of its 

 N.W. side. Here, in the cliffs of Treacherous Bay, 

 the stratified sandstone and conglomerates make 

 their appearance from under the igneous rocks, 

 dipping towards the interior of the island, or S.E. 

 at a slight angle, not more than 5° or 6°. The ig- 

 neous rock is a heavy, dark-coloured hornblendic 

 trap, generally conpact, but here and there slightly 

 cellular, or having a few dispersed crystals. On 

 the N.E. side of Treacherous Bay, the cliffs shewed 

 the igneous rock, resting on the sandstones, and it 

 appeared to have flowed over them as lava. The 

 sandstone was not apparently altered, but the igne- 

 ous rock was much more cellular and cinder-like 

 than usual for two or three feet, above the sandstone, 



