May 2G, 1905.] 



SCIENCE. 



823 



The highest points of this Cordillera are situ- 

 ated in the southern part of New South Wales, 

 not far from the Victorian boundary line, and 

 somewhat exceed 7,000 feet in elevation; the 

 culminating point is Mt. Kosciusko, which 

 attains 7,300 feet. The Snowy Kange, which 

 includes most of this elevated district, con- 

 stitutes the watershed between the interior 

 drainage of the Murrumbidgee and Murray 

 Rivers and that of the Snowy River which 

 empties into the ocean in Victoria near the 

 boundary line between that state and New 

 South Wales. 



The plateau sustains a very scanty vegeta- 

 tion of dwarfed eucalyptus. The climate is 

 very cold, the temperature sinking to — 20° F. 

 in the winter, and the snowfall is extremely 

 heavy. 



The rocks consist chiefly of the rather closely 

 folded Paleozoic sediments which occupy so 

 much space in the Cordillera. Their age 

 ranges from Ordovician to early Carbonifer- 

 ous, and tuifs and intrusive granitic rocks of 

 various kinds are associated with the sedi- 

 ments. 



The so-called Snowy Range is not really a 

 range at all, but a plateau of comparatively 

 gentle relief, a peneplain in fact, with eleva- 

 tion ranging from 5,000 to 7,000 feet, in which 

 the Tumut, Murrumbidgee and Eucumbene 

 Rivers have cut abrupt canyons, the depth of 

 which in some cases amounts to 3,000 feet. 

 That this uplift is of comparatively recent age 

 is proved by the basaltic flows which, near 

 Kiandra, cover the summit of the plateau. 

 The basalt covers an old auriferous river chan- 

 nel which has been traced for 20 miles by 

 means of mining operations, and which has a 

 gentle northward grade. Sand, clay and lignite 

 cover the thin stratum of auriferous gravel to 

 a depth of 150 feet and capping this the basalt 

 flow attains a thickness of about 100 feet. 



Geo. Otis Smith, 



Secretary. 



DISCUSSION AND CORRESPONDENCE. 



CONCERNING THE NATURAL MOUNDS. 



What has been said in Science recently 

 (Nos. 530, 535 and 536, pp. 310, 514 and 551) 

 by Mr. A. C. Veach and Professors Branner 



and Hilgard is of great interest to the writer, 

 inasmuch as he has for some years been 

 making observations on these mounds in Ar- 

 kansas with the hope of reaching a satisfac- 

 tory conclusion as to their origin. They have 

 been observed along the western border of the 

 Tertiary area, along the Arkansas valley, and 

 in the northwestern part of the state. In out- 

 line, they are uniformly circular, and in size 

 are rarely less than fifteen or more than thirty 

 feet in diameter, and usually less than three 

 feet in height. 



The theories of surface erosion, wind origin 

 and human origin have been applied to these 

 with the conclusion that none of them will 

 hold. The uniformity of size and circular 

 outline could not result from surface erosion. 

 For the same reason, as Mr. Veach points out, 

 they could not be the product of wind deposi- 

 tion. Besides, they always occur on clay soil, 

 out of which and upon which, according to 

 the writer's observations, the wind does not 

 form dunes. The fact that they frequently 

 occur in the most undesirable places for hu- 

 man abode, being on ground where both the 

 surface drainage and underdrainage is poor, 

 is in itself sufficient argument against the 

 theory of human origin. The spring and gas 

 vent theory is not tenable in the Paleozoic 

 region, for the reason that Mr. Veach has 

 stated. 



After being forced to abandon the above 

 theories, one of origin by burrowing animals, 

 such as the gopher or prairie-dog, was held 

 for some time, but the examination of a large 

 number of sections disclosed by grading along 

 railroads, wagon roads and cutting ditches 

 through farms furnished no evidence of the 

 material having been worked over, as must 

 have been the case if such were the origin. 

 However, this theory is not yet entirely aban- 

 doned. 



As to the ant-hill theory, there are at pres- 

 ent in the Arkansas valley large numbers of 

 ant-hills from three to four feet in diameter, 

 and often as much as fifteen inches high. 

 These are found on the very soil where the 

 mounds occur. But if the ancestors or fore- 

 runners of the living ants were the builders 

 of the mounds, they must have existed in 



