Geology and .Natural History. 179 



SCIENTIFIC INTELLIGENCE 



I. Geology and Natural History. 



1. The Bermuda Islands. Part IV. Geology and Paleon- 

 tology ; by A. E. Verrill. 168 pp., 88 text-cuts, 12 plates. 

 Trans. Conn. Acad. Science, vol. xii, 1906-7. — Although the text 

 of this work was printed and a number of copies were distributed 

 in March, 1906, the complete work, with all the plates, has only 

 recently been issued (May, 1907).* This part contains a very 

 detailed account of the geology of the island, and the changes 

 they have undergone, by submergence and elevation, erosion, etc. 

 The rocks are nearly all composed of wind-drifted shell sands 

 more or less consolidated, but a narrow belt of marine limestones, 

 formed in shallow water, and containing numerous marine shells 

 and foraminifera, mostly like those now living there, occurs in 

 many places a little above sea-level. The origin and nature of 

 the materials are fully discussed. 



The most noteworthy novelty is the division of the rocks into 

 three distinct geological formations, representing periods parallel 

 with those of the North American coastal area. The earliest, named 

 the " Walsingham " formation, is composed in part of very hard, 

 compact limestones, of seolian origin. In this formation land 

 snails of many species are found, most of which are now extinct, 

 including the large forms of P<ecilozonites Nelsoni, of which 

 three varieties, all extinct, are recognized and figured. This 

 formation was dep osited during a period of marked elevation, 

 probably at least 125 feet above the present level when greatest, 

 as shown by the submerged drainage channels and eroded escarp- 

 ments, submerged peat deposits, etc. This period is considered 

 to be preglacial and probably Pliocene. The larger sizes of the 

 land shells and their abundance indicate a warmer and more 

 moist climate, with abundant vegetation. This was followed by 

 a long period of submergence, ending in a depression rather 

 greater than at present. To this period, named the " Devon- 

 shire," the raised marine limestones, with fossils, are referred, but 

 the seolian rocks of this age cannot be distinguished from the 

 later ones. It probably corresponds to the glacial and Charaplain 

 (or Leda-clay) period of New England. The later seolian rocks, 

 named the " Paget " formation, contain in many places an abund- 

 ance of land shells, nearly all of which are still living on the 

 islands, though some have undergone some changes, recognizable as 

 varietal. The phenomena of erosion in all its forms are very fully 

 discussed and illustrated. The elevated shore cliffs, exposed to 

 heavy seas, furnish excellent object lessons of this kind. New 



" The delay was largely due to a strike in the printing office. 



