at Camp 4 l,.")7o feet, as determined by l)yi3Rometric observa- 

 tion. 



From Camp i Messrs. Lindsay and Helms made a tlying-trip 

 towai'ds the south for about 50 miles. From the nature of the 

 specimens collected by Mr. Helms from actual outcrops, and from 

 the ascertained topographical configuration, the country in this 

 direction seems to change very suddenly in proportionately short 

 distances. Starting from Camp 4, the same class of country 

 extended to ten miles ; next, low sandstone-ridges were traversed 

 for 15 miles, after which claypans, with abundance of crystal- 

 lised gypsum, were conspicuous features, and here traces of an 

 extinct mound-spring were observed. 



Leaving Camp 4 in a chiefly south-west direction, the country 

 travelled over was of the same cliaracter until Camp 12 was 

 reached, namely, granite intersected by greenstone-dykes, which 

 appear as boulders and bosses rising out of sandy plains now and 

 then, but especially in the vicinity of the granitic rocks low 

 banks of travertine occur. In this part of the country the sand- 

 dunes are more numerous, and the intervening depressions are 

 covered with gravel or coarse sand ; their general trend is north 

 and south, and their height from 20 to 25 feet. 



Towards the north the Musgrave Range is visible as a long 

 line of bold peaks shadowed in a dim, blue light ; to the south 

 low, indistinct ranges are noticeable. 



The mean lieight of the plains is here 1,560 feet, by barometric 

 reading, and the granite hills do not exceed 250 feet. 



Travelling from Camp 6 in a southerly direction we passed 

 long, low hills having the shape of a marquee (see fig. 3, pi. 2, 

 fig. 7, pi. 4), and trending east and west. They seemed to be the 

 continuation of the ridges of which Chambers Bluff is the most 

 prominent elevation. They consist of quartzites and sandstones, 

 and have a steep escarpment on the north side of about 50 or 

 70 feet, whilst the southerly .slope is less abrupt. From one of 

 the most elevated of these hills, 210 feet above tlie northern 

 plain, several parallel lines of similar hills were noticeable to the 

 south and west, some f)f them presenting steep, scarped fronts, 

 also on the north ; others were seen afterwards, from the tops of 

 Mounts Watson and Sir Thomas, extending to tlie westward, ' 

 wliich connect them with the Townsend Ridge, whicli was reached 

 later. 



Leaving this range on a noi'th-westerly course, \\-e travelled 

 over sandy plains with wind-drifted, sand-dunes, the intervals 

 between them being tliickly wooded with " mulga," and eventu- 

 ally reached the outlying portions of the Birksgate Range. 

 Mount Watson (see fig. 5, pi. 3), the Birksgate Range (see fig. 

 6, pi. 3), and some smaller contiguous elevations consist of granite 



