470 Notices of Memoirs. 



West of Scotland in Tertiary time reference must be made to the remark- 

 able volcanic vent in Arran, the recognition of which is due to the 

 suggestion of my friend Mr. Peach. This volcanic centre covers an area 

 of about eight square miles, and lies to the south of the granite area of 

 the island.^ The vent is now filled with volcanic agglomerate and large 

 masses of sedimentary material, some of which have yielded the Rhaetic 

 and Lower Lias fossils already referred to, the whole being pierced by 

 acid and basic igneous rocks. One of the interesting features connected 

 with it is the occurrence of fragments of limestone with the agglomerate, 

 which has yielded fossils of the age of the Chalk, thus proving that the 

 vent is post-Cretaceous. There is thus strong evidence for referring 

 the granite mass in the north of the island and most of the intrusive, 

 acid, and basic igneous rocks to the Tertiary period. It furnishes remark- 

 able proof of the Tertiary age of the Arran granite suggested by Sir A. 

 Geikie in 1873.^ The story unfolded by this discovery is like a geological 

 romance. The former extension of Rhaetic and Lower Lias strata and 

 of the Chalk in the basin of the Clyde, and the evidence of extensive 

 denudation in the south of Scotland, appeal vividly to the imagination. 



This outline of the researches in the solid geology of Scotland would be 

 incomplete without reference to the publication of Sir A. Geikie's great 

 work on " The Ancient Volcanoes of Great Britain " (1897), in which the 

 history is given of volcanic action in Scotland from the earliest geological 

 periods down to Tertiary time. To investigators it has proved invaluable 

 for reference. Nor can I omit to mention the new edition of his volume 

 on " The Scenery of Scotland," wherein he depicts the evolution of the 

 topography of the country with increasing force and fascination. In this 

 domain it may be said of the author, " Nihil quod tetigit sed ornavit." 



II. — Egyptian Geology. — We have much pleasure iu noticing 

 " Geological Survey Eeport, 1899, Part III, Farafra Oasis ; its 

 topography and geology, by Hugh J. L. Beadnell," issued in July, 

 1901, by the Survey Department, Public Works Ministry at Cairo. 

 This, the second report issued, follows closely on Part II, and consists 

 of 39 pp., 4 maps, and many sections. The report is divided into 

 Introduction ; Topography, with notes on the Wells, Population, 

 etc. ; Geology ; the Desert between Farafra and Dakhia ; and 

 Geological Summary. The geological summary shows that in the 

 district under notice the lowest rocks met with are correlated with 

 the Danian of Europe. These consist of, from below up, clays and 

 sandstones of Ain el Wadi, with plant remains and silicified wood ; 

 hard blue-grey limestones and White Chalk with brachiopods, 

 lamellibranchs, annelids, etc. Above these come shales, occasionally 

 present, with an abundance of fossils, beds probably representing 

 locally the upper part of the White Chalk. The Eocene is repre- 

 sented in its lower part only by limestones of the plateau with 

 numerous echinids, lamellibranchs, and many foraminifera (Libyan 

 series) at the top, while below come the Esna Shales, in part 

 fossiliferous and with Operculina limestone occasionally at the base. 

 The recent deposits are seen in the soils and clays of springs with 

 recent fresh-water shells, blown sand, and local and un fossiliferous 

 marls and clays. The report will be of the highest value, and like^ 



1 Quart. Journ. Geol. Soc, vol. Ivii (1901), p. 226. 



2 Trans. Geol. Soc. Edinb., vol. ii, p. 305. 



