Correspondence — C. Carus- Wilson. 47 



In a communication entitled " Pseudo-Scolites" [Research, April 1, 

 1889) 1 pointed out that such tubes or " foralites " might be seen in 

 great numbers on sloping, sandy beaches, especially when the sand 

 covers a deposit of shingle, and that they were simply vents formed 

 in the wet sand by the escaping air, which was compressed by the 

 advancing waves. In a given slope of sliingie, covered with a layer 

 of wet sand, there is a certain quantity of air, and this, on being 

 compressed by an advancing wave, escapes through the wet sand at 

 the surface. The advance of the wave increases the pressure, and 

 the confined air escapes from the weakest points at the surface of the 

 sand. Erom the vents thus produced the air issues with considerable 

 energy, as bubbles forced through the water of a retreating wave 

 often show. The receding tide leaves many of these miniature blow- 

 lioles intact, and frequently with a crater-like ridge of sand around 

 their orifices. In some cases these tubes were 4 or 5 inches in depth, 

 and on the more level parts of a beach where firm sand prevailed 

 they were filled up with fine mud, Foraminifera, and minute frag- 

 ments of shell, etc. Under favourable circumstances these tubes 

 might be preserved from futux'e obliteration. 



Such tubes might also be formed in unindurated inland deposits by 

 the escape of compressed gases caused by the decomposition of 

 organic matter, chemical reactions, and by steam escaping from 

 heated areas. 



C. Cahus-Wilsojst. 



Altmore, Waldegrave Park, 

 Strawberry Hill. 

 November 13, 1917. 



Note by Dr. Bather. 

 I must apologise for having omitted all reference to Dr. Carus- 

 Wilson's previously published obervations, due, I regret to say, to 

 pure ignorance of them on my part and presumably also on the part 

 of Professor Hogbom, with whose account they entirelj* agree. The 

 pipe-rock of Sutherland is so well known to British geologists that 

 it was hardly necessary for me to mention it. Dr. Carus-Wilson's 

 reference to it is apparently intended to suggest that the horizontal 

 position of some of the tubes in the Tasmanian rocks may be due to 

 subsequent movement. On this point I have no evidence. 



F. A. Bather. 



BOEING FOE COAL AT PEESTEIGN. 

 Sir, — The alleged discovery of buried stores of coal at the 

 Presteign lime-kilns, suggested by Professor Watts (Geol. Mag., 

 1917, p. 552) as the origin of the local delusion that a bed of coal 

 crops out there, is a possible explanation ; but it is remarkable and 

 lamentable that no tradition of the lime-burning survived among the 

 unfortunate subscribers. Some such storing of fuel may account 

 also for the local belief in the existence of coal at Cad well, 3 miles 

 E.^.E. of Presteign, where pieces of coal in the soil above a quurry 

 in Wenlock mudstones and nodular limestones (containing the usual 

 fossils) were visible in 1915. The coal may have been taken there 

 to burn lime at some remote period. 



