S.'x') (iEOLOGY OF GLASS HOUSE MTS. AND DISTRICT, 



Mc. Beersvah is also entirely columnar. On the N.W. side, 

 near the summit, we see a mass of fine rectangular columns 

 similar to those of Mt. Conowrin. Near the base, however, the 

 columns are tabular, and do, as Mr. Stutchbury has already 

 remarked, lean inwards.* The large tabular columns of Mt. 

 Beerwah consist of a peculiar glistening and soft trachyte which 

 superficially resembles sandstone, so much so that Mr. Stutchbury 

 described them as metamorphic sandstone. They contain large 

 plienocr3"sts of plagioclase up to ^ inch in diameter. The sand- 

 stone outcropping in a gully east of Beerwah dips 25° in the 

 direction of Conowrin. 



(8) Occu7'rence of Basalts in the District. — Mt. Mellum is 

 basaltic. Its height is over 1,200 feet, and from the 500 feet 

 level to the summit we meet with basalt only. The mountain 

 was scaled from the south-east along a ridge which consists of 

 sandstone until a height of 500 feet is reached. The lower basalt 

 (between 500 and 600 feet) is vesicular, as is also the basalt of 

 the summit. Between the two masses of vesicular basalt we 

 meet with, in the ascent, a thick mass of compact columnar 

 basalt. At the junction with the sandstone we tind the latter 

 strongly metamorphosed — turned, in fact, into quartzite. 



Basalt-flows from Mt. Mellum have once extended south beyond 

 Coochin. They are now denuded except for isolated patches of 

 basalt and scattered basaltic nodules, but they have impregnated 

 the subjacent sandstones with iron, and turned the sandy soil 

 bright red. 



Mt. Mellum probably represents a basaltic extinct volcano. 

 It -seems to me unlikely that it represents a flow for the following 

 reasons : — 



1. In the ascent, horizontal columns only have been met with. 



2. Its isolation and seeming freshness. 



• New South Wales Geological Survey. Fourteenth Trimonthly Report, 

 dated Durandur, 1st August, 1854. Legislative Council Papers, N.S.W., 

 19th September, 1854. 



