Features and Groioth of Lake Goongarrie. 117 



(1) Gully deposits consist of the detritus accuinulated in the siuall 

 longitudinal valleys of the " high " lands, as the transverse valleys 

 ^re V-shaped and have but little detritus. The longitudinal valleys 

 iiave reached a later stage of erosion, and they are flat-bottomed, 



although narrow, with fine and coarse detritus from two to six feet 

 >deep on their floors, through which the occasional streams cut their 

 way. 



(2) The piedmont plains deposits really include the deposits 

 under (3), but for convenience the piedmont deposits are here re- 

 .stricted to the gently sloping narrow plains of coarse detritus, up 

 to six or eight feet thick, which lie opposite to the '* high " lands, 

 and which have been formed by a coalescence of the coarse alluvial 

 fans laid down by the small streams as tliey debouch from the 

 " high " lands on to the lake. These piedmont deposits are 

 traversed by the continuations of the small streams from the hills, 

 and in places at their junction with the lake have been truncated 

 so as to now form low cliffs from four to six feet high. 



(3) These deposits are much more extensive than either of the 

 ■other two, and they consist of a veneer (for they are generally not 

 more than a foot or two thick) on the soft bedrock of the lowlands. 

 These lowlands form, long gentle slopes, with a diminishing fall to 

 the east, and usually merging into the '* 1 'Ulard-table " rock floors 

 of the lake. On the west they terminate in cli,ffs, which form the 

 eastern boundary of a low tableland. 



(4) The samphire flats, so named from the typical plants growing 

 there, are found around the edge of the lake, usually in association 

 with the sand ridges. These flats have not been closely examined, 

 and the question of their origin requires further consideration, but 

 they appear to consist of sands and clays with, in places, a con- 

 siderable amount of gypsum, both in the crystalline form, and as 

 ■*'kopi," the powdery form. Where gypsum cements the loose 

 materials together, these flats become traversed by shallow water 

 channels, along which detritus is carried into the lake, thus help- 

 ing to build up the floor of the lake, and to assist its migration. 



Nature and Distribution of the Sand Ridges 



The sand ridges at Goongarrie ai'e almost entirely restricted to 

 the lake area, and those now described are associated with the arms 

 of the lake on its western side. They comprise small low, irregularly 

 shaped ridges from about three to eight feet high, which, going 

 ■eastward, pass gradually into long and regularly shaped ones from 



