THE DESERT SANDSTONE. 319 



fresh ; but after some time they become brown, as every one can 

 see wherever sections of ash-beds are exposed, and there are few 

 parts of the island without them. On the sides of the extinct 

 craters the crevasses and gullies cut by the rains form gorges, 

 which have been a subject of comment and admiration to every 

 traveller. The precipices and escarpments in these ash-beds form 

 a wild scenery of the grandest kind. The gorges however are in 

 some cases cut down in the loose and friable ash for hundreds of 

 feet and more, exposing in this way different coloured beds of black, 

 white, brown, or yellow, according to the age of the formation. I 

 have seen gorges of 1,000 feet deep at the very least. Perhaps 

 the whole of this is the result of a single eruption. 



As an illustration of the manner in which ash-deposits will 

 accumulate and form mountain ranges I may take Java as an 

 instance, about which so many erroneous impressions prevail. In 

 a work entitled " The Eastern Archipelago,"* one of the popular 

 scientific series that convey to the public the most astounding 

 information under the name of useful knowledge, it is stated that 

 " throughout its entire length Java is traversed by two chains of 

 mountains, which occasionally unite, but more frequently run at 

 some distance from each other and send spurs and branches of the 

 most various outline down to the shore." This is an impression 

 as prevalent as it is incorrect. There is no mountain range 

 extending the length of the island, in fact the last hundred miles 

 of the eastern end is formed by four craters making a rough 

 quadrilateral. To the west of Surabaya there is an extensive 

 mountain range which has not any extinct crater for 100 miles or 

 more. It is deeply scored by valleys of erosion, showing that it 

 is built up of fine ash sands in places, or by a accumulation of 

 coarse material when the volcanic period was indeed one of nature's 

 periods of fury. In other parts of the island too, there are detached 

 hills of volcanic material, which have evidently never been a crater 

 or an outflow of lava. They are accumulations of ashes which 

 mark former eruptions, and their resemblance at times in shape 

 and material to the Desert Sandstone is very striking. As a rule 

 they are about 4,000 feet high, though their surface is very ragged 

 and irregular, owing to the wearing down by rainfall which here 

 averages nearly 100 inches per annum. 



Professor Liversidge in his " Minerals of New South Wales, "f 

 mentions the occurrence at New Ireland of a pale brown calcareous 

 mudstone, looking at first sight much like a sandstone containing 

 much volcanic ash. He also mentions a sandstone which must 

 have had a similar origin, since the dark thin parallel planes of 



* London : T. Nelson & Sons, 1880. 

 f London, Triibner & Co., 1888, p. 254. 



