32 THK VICTORIAN NATURALIST. |Vol. XXIV. 



Reference to the diagrammatic section will illustrate the fairly 

 simple structure of some of the primitive valleys of this area. The 

 northern portion of the Wellington Range affords a good example 

 of this type. To the south of the Trig. Station there is a wide, 

 open valley of well-grassed snow-plain country, situated at an 

 elevation of nearly 5,000 feet above sea level. It falls somewhat 

 gently southwards for hetween two and three miles, following the 

 strike of the rocks. It then turns sharply to the west through a 

 gap worn in the western scarps of the Wellington Range. This is 

 the Nigothoruk Creek, which drains the snow country into Lake 

 Karng. The western edge of the valley is bounded by the ridge 

 formed by the upturned edge of a thick bed of porphyritic rhyolite, 

 while the eastern consists of a parallel scarp of sandstones, mud- 

 stones, and conglomerate about a mile to the east. The present 

 stream bed has cut a deep V-shaped valley along the eastern side 

 of the broad, rounded valley. It follows fairly closely the contact 

 of the igneous sedimentary rock, though occasionally the con- 

 glomerate lies to the west. This course is held till the sharp turn 

 is made across the strike of the rocks. 



Another similar feature, but on a somewhat larger scale, is found 

 at the head waters of the Moroka. Immediately to the west of 

 the Trig. Station lies the deeply incised source of the Moroka. 

 Here it is also a strike valley for some distance, with the 

 sedimentaries on the east forming the scarp, and the rhyolite on 

 the west forming a dip slope. The valley continues as such for 

 perhaps two or three miles northerly, and then turns sharply to 

 the east, and subsequently follows a great S-shaped canyon 

 course, with, at first sight, no apparent connection with the 

 structure of the rocks. Parallel with the upper strike course 

 there is a wide high-level snow-plain valley, conforming to the 

 strike, and only separated from the deep Moroka valley by a low 

 ridge. This has been cut through in two places by the head- 

 ward erosion of the Moroka tributaries, by which the old high 

 valleys is now drained over its eastern rim into the Moroka. The 

 general elevation of the plateau valley varies from a little over to 

 a little under 5,000 feet. The western scarp has also been 

 broken towards the northern end by a stream which drains into 

 the Wellington. The whole of this valley is broad and open, 

 with a rounded outline and a well-grassed surface. It is well 

 watered by small streams rising from numerous springs, and 

 forms a most pleasing contrast to the rugged and difficult country 

 which surrounds it. The richer grass of the valley is in some 

 measure due to the presence of basaltic rock (melaphyre) along 

 part of its floor. 



None of these strike valleys are of great extent ; they appear 

 to be but the remnant of old valleys which have been very much 

 cut into by the advanced plateau dissection. Their open 



