BY H. I. JENSEN. 859 



Creek and Grattai (Couradda) is as rugged as that of Bullawa 

 Creek, but the creek valley itself is a plain. Its level nature is 

 apparently due to the fact that it was already a deep, broad 

 valley when the eruptions took place, and though lavas entered 

 it both north and south they by no means sufficed to fill it. 

 This conclusion is borne out by the existence of volcanic trachytes 

 at the level of the creek below Dripping Rock. The range between 

 Rocky Creek and Bobbiwaa Creek has isolated trachyte cappings 

 which are flows from dykes, but where the road crosses it there 

 is no such cap (altitude 2,200 feet). It has been removed by 

 denudation. The strata at the pass consist of Permo-Carboniferous 

 sandstones and shales with a coal seam about 6 feet thick out- 

 cropping on the top. The dip appears to be S.E. at angles not 

 exceeding 10°. A great laccolitic mass of basic rock similar to 

 that at Dingo Creek and exhibiting similar variations intrudes 

 the Permo-Carboniferous strata at the head of Bobbiwaa Creek, 

 and attains a thickness of 400 feet. The numerous mountains 

 (Dripping Rock, Grattai, etc.) lying north of Upper Bobbiwaa 

 Creek consist partly of sandstones with basic sills and partly of 

 sandstone with trachyte sills and flows. Some of the peaks are 

 wholly composed of trachyte. The cappings of columnar trachyte 

 all slope to the N. W., indicating an original slope in that direction 

 before the outpourings, or that the flows came from the S.E., near 

 the head of Bobbiwaa Creek. Across the range in the Rocky Creek 

 valley the country is mountainous but not rugged. It consists 

 essentially of Permo-Carboniferous rocks with basic sills and later 

 trachyte dykes. 



Maule's Creek. — The country surrounding this creek must also 

 be dealt with separately. To Maule's Creek I proceeded from 

 Tarriaro and struck the creek a few miles below its junction with 

 Horse-Arm Creek. Between Tarriaro and this junction the 

 country is sandy, very gently undulating, on the whole poor, and 

 traversed by a number of shallow gullies heading in the moun- 

 tains to the north-east; the gullies are devoid of water except 

 when torrential rains occur and send the water down in sheets. 

 Many of these watercourses are purely relics from a time when 



