83 
Lake Amadeus itself was discovered and named by Mr. Ernest Giles in 1872, 
when it proved an insuperable obstacle to him in his westward course towards 
Western Australia. In 1873 it was crossed by Mr. Gosse at a narrow neck 
near its eastern extremity ; but in the next year Mr. Giles was again forced to 
retrace his steps, the bed of the lake, where examined by him, being found to 
be so boggy as to be impassable. In 1889 Mr. Tietkens examined the western 
portion of the lake, and was consequently able to define approximately its true 
outline, which had previously been extremely hypothetical. His examination 
of the lake resuited in the shortening of its length, as shown on the maps up to 
that time, by more than 100 miles. 
Its extreme western portion, which was previously supposed to be situated 
about 128° 10’ in Western Australia, and to be about twenty to thirty miles 
wide, is now known to be situated in South Australia, about 130° 18’, and to be 
only from two to three miles wide. 
According to Mr. Tietkens, its extreme length is about ninety-two miles, 
while its width varies from two to fifteen miles, the maximum width of fifteen 
miles occurring about the 131st meridian. At the narrow neck, however, where 
we crossed, it is not more than three-quarters of a mile wide. 
The area of the lake is approximately 700 square miles, and its altitude above 
sea level must be more than 1,000ft. 
One set of calculations of its elevation were based on Mr. Winnecke’s figures 
for the altitudes of the camps at Bagot Creek and Reedy Hole, and on the 
differences between the barometrical readings at those places and at Lake 
Amadeus; while another set were based on the barometrical readings given by 
Mr. Tietkens in his journal, &c. 
As far as known, Lake Amadeus receives the drainage of a few small creeks 
only, as no rivers of any importance have up to the present time been dis- 
covered within the area of its basin. The view of the lake gained from the 
neighboring sandhills is a very remarkable one. Stretching away to the east 
and west as far as the eye could discern was a dazziing white, flat expanse, on 
whose surface no water could be seen, but in its place a coating of a white 
saline material, which on analysis proved to be composed almost entirely of 
common salt, with a small amount of sulphate of lime (gypsum). On closer 
examination the saline vrust was found not to exceed a quarter to half an inch 
in thickness, under which was a red argillaceous sand passing down into similar 
material of a grey color. The surface of the lake was found to be tolerably 
firm, the horses only sinking to the depth of a few inches. On each side of the 
lake the sandhills rise to a height of 50ft., and have a nearly east and west 
trend. 
id 
E.—CLAYPANS. 
After the description of the lakes it is necessary to say a few words about 
those miniature lacustrine features known as ‘‘claypans.’’ ‘They are usually 
in the form of flat shallow depressions, often nearly circular, but in the majority 
of cases of irregular outline, and usually devoid of vegetation. They are 
generally surrounded by loamy plains or sandhills, and while they are more 
frequently met with throughout the Cretaceous area, they are still not un- 
commonly found on the plains and in the valleys of the ranges within the 
Ordovician area. Mr. Streich suggests that claypans owe their existence* to an 
* Trans. Roy. Soc. of South Australia, vol. xvi., part ii., p. 90. 
