H. J. L. Beadnell — Nature's Rock-borings in the Fayum. 31 



Steenstrtjp, J. (1839). "Bidrag til Cirripedernes Historie i Fortid og Nutid, Ferste 



Bidrag. Anatiferidse og Pollicipedidse fra Kridtperioden " : Kreyer, Natur- 



historisk Tidsskrift, ii, pp. 396-415, pi. v. 

 Whiteaves, J. F. (1889). " On some Cretaceous Fossils from British Columbia, 



the North-West Territory and Manitoba " ; Contributions to Canadian Palseon- 



tology, i, pt. ii, pp. 151-96, pis. xx-xxvi. 

 "Woodward, H. (1908). " On a large Cirripede belonging to the genus Loricula, 



from the Middle Chalk (Turonian), Cuxton, near Kochester, Kent": Geol. 



Mag., Dec. V, V, pp. 491-9, text-figs. 1, 2. 

 Zittel, K. A. (1884). " Bemerkungen iiber einige fossile Lepaditen aus dem 



lithographischen Schiefer und der oberen Kreide " : Sitz. d. math. phys. 



Classe d. k. b. Akad. der Wissensch. zu Miinchen, xiv, Hit. iv, pp. 577-89, 



text-figs. 1-5. 



VI. — On the Origin op the Cylindrical Cavities in certain 



Sandstones of the Fayum, Egypt. 



By H. J. Llewellyn Beadnell, F.G-. S. 



T'N an article published in a recent number of this journal, 1 Dr. Henry 

 J_ "Woodward discusses the origin of the curious cylindrical cavities 

 which occur in such profusion in certain concretionary blocks of sand- 

 stone and on exposed rock-surfaces at two distinct levels in one or two 

 localities in the Fayum depression. These perforated rocks, first noted 

 by Schweinf urth, were examined by me some ten years ago and referred 

 to as "apparently the work of marine boring mollusca" in my memoir 

 on the region in question. 2 Both Dr. Scbweinfurth and I had con- 

 siderable misgivings in regarding the cavities in question as shell- 

 borings, but in my case, and I believe in his also, this explanation 

 appeared to involve fewer difficulties than any other which suggested 

 itself. 



Dr. "Woodward, after comparing these cylindrical cavities with 

 certain reed-casts found by Mr. J. E. S. Moore on the shores of Lakes 

 Kivu and Tanganyika, pronounces that the perforations in the rocks of 

 the Fayum are identical in character with the latter, and concludes 

 that they represent the casts of reeds which grew on the shores of the 

 existing lake, the Birket el Qurun, or on those of its more extensive 

 predecessor, Lake Moeris. 



Knowing Dr. Woodward's achievements in the interpretation of 

 obscure fossil remains — witness his solution of the problem of the 

 Sherringham flint pebble — I hesitate to question his verdict in the 

 case of the Fayum perforations. His explanation would, indeed, be 

 more than welcome, as it would to some extent remove a difficulty 

 arising from the assumption that these cavities are the work of 

 marine boring mollusca, i.e. the necessity for admitting a considerable 

 submergence of the region in Pliocene or post-Pliocene times. 3 



1 "On some supposed Pholas -horings from the Shores of Birket el Qurun, the 

 ancient Lake Moeris, of the Fayum, Egypt": Geol. Mag., September, 1910, 

 pp. 398-402. 



2 "The Topography and Geology of the Fayum Province of Egypt": Survey 

 Department, Cairo, 1905. 



3 Submergence of the region in Middle Pliocene times to a level of between 60 and 

 70 metres (above present sea-level) is, I think, satisfactorily established on the evidence 

 of the marine shell-bearing deposits of Sidmant, etc. Submergence to a level of 

 170-80 metres rests at present on somewhat unsatisfactory grounds, mainly (a) the 

 supposed shell-borings at about 112 metres, and (b) the remarkable gravel terraces 

 extending up to 180 metres above present sea-level. 



