526 Correspondence — Dr. F. A. Bather. 



agreed that, although nepheiine cannot possibly be determined in 

 any of the author's micro-sections, yet the general resemblance of 

 the latter to those of the felspathoid-bearing basalts of the 

 St. Monans and Elie district is so remarkably close as probably to 

 place beyond question their related origin. 



When discussing the geological age of the Bock and Spindle vent, 

 the author said he was inclined until recently to concur with Sir A. 

 Geiltie in placing it along with other East Fife necks in Permian or, 

 at all events, in post-Carboniferous time. Bevision of this opinion 

 would, however, now appear necessary. A careful examination of 

 the Spindle basalt reveals the exceptionally interesting fact that 

 there are enclosed in it, apparently directly, numerous fish teeth in 

 a condition of excellent preservation. Dr. Peach believes he has 

 identified Megalichthys and Psammodus in the specimens collected. 

 Should these fossils, on fuller investigation, prove not to be derived, 

 then the vent must be carried back in age to the period of the' 

 Carboniferous Limestone. 



CORBBSPOlTDEnSrCEl. 



SALT-WEATHERING AND SUPPOSED WORM-BORINGS IN 

 AUSTRALIA. 



Sir, — The interesting notice, signed W. H. W., of Mr. E. J. Dunn's 

 "Geological Notes, Northern Territory, Australia" (Gkol. Mag., 

 March, 1917, p. 134), led me to communicate with Mr. Dunn, who 

 has kindly sent me copies of his recent papers, on which I venture to 

 offer the following remarks. 



The appearance of contortion observed on the surface of a two-inch 

 core in presumed Carboniferous rocks, and interpreted by Dr. Jensen 

 and Mr. Dunn himself as due to the borings of worms, reminds one 

 rather of some pieces of the Cotham Stone or Landscape Marble (see 

 Horace B. Woodward, Geol. Mag., March, 1892, p. 110). The rock 

 before its disturbance appears to have consisted of thin layers of sand 

 alternating with thin layers of black shale. The latter, being 

 carbonaceous, may well have contained in places a considerable 

 amount of decaying organic matter. Consequently the explanation 

 of these disturbances may be the same as that put forward by 

 Mr. Beeby Thomson for the Cotham Marble (August, 1894, Quart. 

 Journ. Geol. Soc, vol. 1, pp. 393-410). That is to say, bubbles of 

 gas springing from the decomposing carbonaceous matter pass through 

 the overlying laminae and throw them into confusion. When the 

 streams of bubbles are concentrated in definite places naturally 

 a tubular form is assumed; hence the resemblance to worm-borings. 



Here one may recall the somewhat similar explanation which 

 Professor A. G. Hogbom has given of the Scolithus sandstone and 

 the Pipe-rock (1915, Bull. Geol. Inst. TJpsala, vol. xiii, pp. 4.5-60). 

 And it is perhaps appropriate to mention here that in 1911 Mr. W. H. 

 Twelvetrees, Government Geologist of Tasmania, sent to the Natural 

 History Museum two specimens of "pipe-stem sandstone" of 

 supposed annelid origin, but showing in thin section no structure 

 other than grains of sand. "For the most part," said Mr. Twelve- 

 trees, "the tubes are vertical to the bedding, but occasionally we 



