144 R- A. WEA.RNE AND W. G. WOOLNOUGH. 



and conglomerate containing angular masses three feet in 

 diameter. A steep escarpment exists to the north and 

 west, and a ridge connects this mountain on the southern 

 side with the lower slopes of Mount Mitchell. Johnston 

 Greek and Clayton Gully rise in the elbow thus formed. 

 A perfect view of the well defined U-shaped mature valley 

 of Cunningham's Gap can be seen from the summit of 

 Mount Matheson. 



Mount Mitchell (4,000 feet). — A splendid section of the 

 volcanic series and the associated sedimentary rocks is 

 revealed in Gap Creek (the eastern one of this name) and 

 the wonderful escarpment of Mount Mitchell itself. The 

 Walloon stage of the Ipswich coal measures is distinctly 

 intruded and capped by trachyte, and these in turn by 

 basalts. A fairly thick seam of coal outcrops about one 

 mile below the "Second Palls." It is intruded by a dyke 

 of basalt which has opened out into a sill along the seam. 

 Several basalt dykes occur running roughly north and south 

 at right angles to the creek, and each in turn causes the 

 formation of a pretty waterfall. 



Cunningham 1 s Gap consists of a perfectly shaped U 

 situated between Mounts Oordeaux and Mitchell, the trough 

 being 1,500 feet below the summits of those mountains. It 

 presents one of the finest examples of an Air Gap to be 

 seen in any part of Australia. At the lowest point of the 

 gap trachyte breccia is met with. The base of Mount 

 Mitchell is composed of alkaline trachyte, tuff and breccia 

 for a thickness of about 1,500 feet, and this in turn is capped 

 by about 1,000 feet of basalt. The entire thickness is made 

 up of a very considerable number of independent beds of 

 volcanic material, each one practically horizontal. The 

 summit of Mount Mitchell consists of a narrow ridge run- 

 ning north and south. Viewed from the east it shows a 

 broad rounded summit with a vertical escarpment of about 



