Vol. 70.] PROCEEDINGS OF THE GEOLOGICAL SOCIETY. Xcix 



The List of Donations to the Library was read. 



The President announced that the Council had awarded the 

 Proceeds of the Daniel Pidgeon Fund for the present year to 

 Percy George Hamnall Boswell, B.Sc, F.G-.S,, who proposes 

 to investigate the Stratigraphy and Petrology of the Lower Eocene 

 Strata, of the North-Eastern Portion of the London Basin. 



Prof. J. W. Judd, C.B., F.R.S., gave the following general 

 account of the Geology of Rockall:— 



'Rockall is a small isolated rock in mid- Atlantic, lying 184 miles west of 

 St. Kilda ; it has a circumference of only 100 yards and a height of 70 feet, 

 and, except in the very calmest weather, is quite inaccessible. It is the haunt 

 of sea-birds and, with its whitened top, resembles a sailing ship, for which it 

 has often been mistaken. The rock rises from a bank (the " Rockall Bank "') 

 upon which there are several dangerous reefs. 



' More than 300 years ago it was reported that a large island occupied the 

 site of Rockall, and, for a hundred years or more, all Atlantic charts repre- 

 sented this island, which was named " Busse Island/' with a number of other 

 islands and islets, as present in the North Atlantic. Taking these supposed 

 facts in connexion with the famous classical stories of an "Atlantis," the 

 theory was often advanced that the North Atlantic was an area of sub- 

 sidence, and that the reported islands — and, in the end, Rockall — were the 

 last vestiges of the famous vanished continent. Modern research has, how- 

 ever, quite disposed of this fantastic theory. 



' Nevertheless, Rockall is of considerable interest, especially to geologists. 

 In 1810 Basil Hall, then a young officer in H.M.S. Endymion, obtained a 

 fragment from this rock, which later found its way into the collection 

 of the Geological Society. More than 30 years afterwards, the specimen 

 was recognized ; it was then mislaid for another 30 years, and in 1895 was 

 brought to me by the late Prof. T. Rupert Jones. 



' He not only carefully studied all the literature connected with Rockall, 

 but was able to trace two other specimens of the rock, the loan of which 

 he obtained and brought to me. They had been procured by two of the 

 officers of H.M.S. Porcupine in 1868 during- the survey of the North Atlantic. 

 The microscopic study of these specimens shows that in Rockall there exist 

 rocks of exceptional interest, which are not represented in our islands, but 

 have analogues in the Christiania district of Norway, where they have 

 been so well studied by Prof. W. C. Brogger. These rocks, as shown by 

 microscopic study and by a chemical analysis made by Mr. Makins, consist 

 essentially of three minerals — quartz, the felspar albite, and the rare soda- 

 pyroxene ffigirite, with its dimorphous form acmite. The rock, therefore, re- 

 sembles the soda-granite and the grorudite of Prof. Brogger — but, in deference 

 to the opinion of the distinguished Norwegian petrographer, a distinct name 

 was given to it. 



4 In 1896 an attempt was made to obtain further specimens of the rocks of 

 this islet by members of the Royal Irish Academy ; but, although many 

 valuable observations were recorded, it was found, after two voyages had 

 been made to Rockall, quite impossible to land and obtain specimens. 



' Dredging operations have yielded many specimens from the Rockall Bank, 

 and these were examined by the late David Forbes and Prof. Grenville A. J. 

 Cole. The abundance of basalt-fragments among these dredgings suggests 

 the possibility of Rockall belonging to the same petrographical province as 

 St. Kilda, Iceland, the Inner Hebrides, and the North of Ireland ; hitherto, 

 I believe, no rocks resembling " rockallite'" have been found in this province 

 On the other hand, the existence of borolanite and other alkaline rocks in 

 the Northern Highlands suggests the possibility of Rockall being the western 



