THE DESERT SANDSTONE. 301 



" It will be seen that the heights besfiti to increase rapidly 

 from the 95th mile, and continue to Pine Creek, so that the 

 average rise, which is about five feet per mile, is less than three 

 feet per mile for the first 100 miles, and more than six feet per 

 mile for the next 50 miles. This is owing to the commencement 

 of ranges which are connected with most of the mineral country 

 in the Territory. These ranges are a series of parallel ridges 

 having a south-south-easterly trend, and rising to a height of 

 from 200 to 600 feet above the plains, though the latter height 

 is exceptional. This mountainous area is about 20 miles in 

 width, from east to west, and 40 miles in length from north to 

 south ; in it are contained the sources of most of the small 

 tributaries of the Adelaide and Mary, which are rivers with a 

 north and south direction. The Adelaide may be said to take 

 its rise in the midst of this chain, and the Mary to the eastward 

 and southward. 



" The ridges and ranges are separated in their northern portions 

 by somewhat wide alluvial flats or valleys, but to the south-east 

 the ranges are closer together, higher and more abrupt, besides 

 being exceedingly stony and barren. Thus the country south-east 

 from Mt. Wells, as far as the Mary River, is exceedingly rugged, 

 and many of the ranges and valleys almost inaccessible. The 

 most closely metalled road would not be more deeply and thickly 

 covered with stones than the valleys and ranges. Several long 

 and high spurs (500 feet above the plain) are continued to the 

 eastward into the valley of the Mary River, but at about 100' 

 miles from Southport the ranges decline to the level of the plain. 



" At the sources of the Mary, the river takes its rise amid flat- 

 topped cliffs of the most picturesque description. The view along 

 the stony white gorges has few parallels in Australia. The 

 valley of the river is hemmed in by straight cliffs of castellated 

 outlines some 150 or 200 feet high. There is often a slope or 

 talus at the bottom, but they are only accessible in a few places, 

 and the valley is for the most part fertile and shaded by fine 

 graceful palm trees ; springs bubble out from the shady thickets 

 at the foot of the cliffs, giving rise to streams many feet wide, 

 and deep from their sources. The valley is strewn to a 

 bewildering extent with huge boulders and masses of rock, which 

 have fallen down from above, because the magnesite is very 

 brittle, with a foundation of loose and friable sandstone. Thus 

 no very long time would be required for the springs to crumble 

 and break away the edge of the table-land, or scoop away the 

 valleys as we see them now. 



" The springs, therefore, I believe to be the origin of the cliffs 

 and gorges at the heads, not only of the Mary but of the West 

 and South Alligator Rivers, and many besides. The magnesite 



