35 



sandliills occur the sands are bound together by the odious 

 spinifex (Triodia irritans), whicli grows in tufts about two feet 

 in diameter. 



This system of parallel ranges borders the Macdonnells on the 

 south side throughout their whole extent. The drainage is to 

 Lake Eyre, except the exti-eme western portion, which trends 

 towards Lake Amadeus, another basin analogous to Lake Eyre, 

 but at a higher level, being about 600 feet above the sea. The 

 slope of which this division is formed may be considered to range 

 from about 1,000 feet above sea at its lower edge to about 2,000 

 feet at its upper limit where it abuts on the Macdonnell Ranges. 



III. The Central Plateau. 



This plateau, of whicli the Macdonnell Ranges forms the 

 southern face, is of a triangular shape, as far as its limits are at 

 present known. The apex ternnnates between Alice Springs and 

 the Queensland boundary, but towards the base it extends into 

 regions still unexplored. Its mean altitude verges close on 3,000 

 feet, and the highest points are along the Reynolds and Strang- 

 ways Ranges to the northward of the Macdonnell system. Mount 

 Oardiner, in the former range, rising over 1,100 feet above the 

 plain at foot, as determined by Mr. W. C. Gosse. The Reynolds 

 Range, prolonged through the Strangways and Hart Ranges, has 

 a general direction of E.S.E., while that of the Macdonnells being 

 nearly east and west, a convergence of the two systems takes 

 place in that section termed the Hart Ranges. The creeks 

 originating in the Macdonnells, except those near the western 

 •end, run down into the Lake Eyre basin. The western drainage 

 is towards Lake Amadeus, and it is probable were the supply of 

 running water sufficient a large creek would traverse the whole 

 length of the elevated plain between the Macdonnells and Rey- 

 nolds Range and rounding the Macdonnell's western end fall 

 into the Amadeus basin. North of the Reynolds Range the 

 Lander, Hanson and Woodforde Creeks lose themselves on the 

 plateau, but more eastward still the creeks originating on the 

 north slopes of the Strangways and Hart Ranges being united 

 into two large channels — the Sandover and Plenty — after a short 

 northern course turn eastward, and rounding the apex of the 

 plateau, enter the long sandy trough descending to Lake Eyre, 

 and in which the main line of drainage is termed the Marsliall 

 River. This trough is a most desolate region of sand and spini- 

 fex, and appears to swallow up all the waters brought down by 

 the Finke, Todd, Elder, Illogwa, Plenty and Sandover Creeks, 

 which drain two sides of the great plateau. The tropic of Capri- 

 corn passes over the plateau just north of the Macdonnell ridg-es, 

 and as might be expected of a region thus elevated under the 



