BY H. C. RICHARDS. 113 



resting on this, numerous flows of sub-basic and basic 

 rocks. The upper series may contain twenty or more 

 different flows, and individual flows may attain a thickness 

 of 100-120 feet, though usually they are much less than 

 this. These separate flows result in a series of ledges being 

 formed along the cliff faces. 



In the south-eastern part of the area, even in the areas 

 free from volcanic rocks, the topography is very young 

 and this is especially so in the upper parts of Little Nerang 

 Creek, Mudgeeraba Creek, and Currumbin Creek. The 

 youth of the valleys results from the resistant character of 

 the Palgeozoic schists, and is contrasted very sharply with 

 the mature valleys of the streams in the areas of Mesozoie 

 sediments. 



The relationship between the vegetation and the rocks 

 is a very striking one. The volcanic rocks are usually 

 clothed with scrub, the sub-basic and basic rocks being 

 thickly coated with true scrub, and the acid and sub-acid 

 rocks with either bastard-scrub or forest timber. The 

 Mesozoie and Palai'ozoic rocks are clothed with the normal 

 forest timber. The value of selections on rhyolitic country 

 is not nearly as high as that of selections on andesitic or 

 basaltic country, although all other conditions may be 

 similar. The part which the volcanic rocks have played in 

 the production of the soils of the rich valleys of this area 

 is, of course, very great, and a close relationship between 

 the fertility of the soil and the rock is observable. 



IV. EARTH MOVEMENTS. 



Dr. Jensen'' has discussed the faulting near Mount 

 Flinders and west of Ipswich, while Wearne ^'^ and Wool- 

 nough have shown the extensive faulting which has gone 

 on in the western and north-western portions of the area. 

 The author has obtained evidence which is in general accord 

 with the conclusions arrived at by these investigators. 

 Just to the north of Brisbane near Albion, a fault line in a 

 north and south direction is known, but this is of no great 

 importance. 



" Proc. Linn. Soc, N.S.W., xxxiv., p. 68. 

 " Op. cit., pp. 140, 141. 



