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SCIENCE-GOSSIP. 



GEOLOGY 



CONDUCTED BY EDWARD A. MARTIN, F.G.S. 



To whom all Notes, Articles and matirial relating to Geology, 

 and intended for Science-Gossip, are, in the first instance, 

 to be addressed at 69, Bensham Manor Road, Thornton Heath. 



Rocks of Sutherland and Caithness. — The 

 history of the rocks of Sutherlandshire and Caith- 

 ness is traced out in a popular and acceptable 

 fashion in H. M. Cadell's " Geology and Scenery 

 of Sutherland " (David Douglas, Edinburgh). 

 Without entering too deeply into the great contro- 



eastern districts, where also perched blocks and 

 morainic mounds both testify to the effects of the 

 Glacial period here. Along the eastern seaboard is 

 a narrow tract in which Middle Lias (400 to 500 

 feet), Lower (120 feet), Middle (400 feet), and Upper 

 Oolites (1,000 feet), extend from Golspie to the 

 Ord of Caithness. The shales and sandstones of 

 the Lias are full of plant remains, sometimes 

 forming thin layers of vegetable matter. It is, 

 however, the contents of the succeeding Lower 

 Oolite which have rendered these Secondary beds 

 famous. The shales become increasingly car- 

 bonaceous, until finally the coal-seam of Brora 

 is reached at their summit. Mr. Cadell states that 

 its existence was known as early as 1529. The 

 maximum thickness of the seam is 3J feet, and is 

 divided into two parts by a layer of iron pyrites 

 about six inches thick. In places it seems to be 

 made up of the crushed stems of Equisetites 

 colwnnavis, and, unlike the coal-measure seams, 

 is made up of drifted vegetable remains, spread 



' ~ 



Peak of Suilven, with Ice-worn Gneiss in Front. 

 (From Cadell's " Geology and Scenery of Sutherland.") 



versy over the age of the Eastern Schists, the main 

 conclusions are shown in pleasing style. By the 

 kindness of the publishers, we are enabled to 

 reproduce two of the many excellent illustrations 

 which are to be found in the book. The first 

 represents the peak of Suilven or the " Sugar 

 Loaf," composed of horizontal courses of Torridon 

 Sandstone (pre-Cambrian) and standing " like a 

 giant sentinel in a heaving sea of gneiss." It is about 

 2,400 feet high. The conglomerates and breccias 

 of this formation rest immediately upon the 

 Archaean gneiss, passing up into grits and fine- 

 grained sandstones. Evidence is not wanting of 

 effects of the glacial plough in Sutherland. On 

 the west the boulder-clay has been all but swept 

 away, but the hummocky ice-worn gneiss of the 

 west is shown well in the illustration. The boulder- 

 clay is only found in any quantity in the lower 



out as a true aqueous deposit over the sea-bottom. 

 The other illustration shows the Brora coal-pit, from 

 which, according to Lyell, upwards of 80,000 tons 

 of coal had been extracted. 



Geology of Llandudno. — At the meeting of 

 the Geological Society, on May 4th, a paper was 

 read by Mr. G. H. Morton, F.G.S., on "The 

 Carboniferous Limestone of the Country around 

 Llandudno." The Carboniferous Limestone from 

 Llangmynech to Prestatyn, and around the Vale of 

 Clwyd, Abergele and Llanddulas, shows well the 

 subdivisions of " Lower Brown," " Middle White," 

 and " Upper Grey," along the whole distance. At 

 Llandudno the precipitous Great Orme's Head 

 presents fine sections of the Carboniferous Lime- 

 stone, and these subdivisions may be easily 

 examined in a continuous series of cliffs, ridges and 



