66 



HARD WICKE 'S S CIENCE - G OS SIP. 



tensis," says of the plant, "on Freshwater Downs in 

 various places, as near the Needles Plotel and Light- 

 house, but scarcely an inch high, being browsed 

 down by sheep " ; and he further adds in a note at 

 p. 291, "On the bleak and lofty Downs, at the 

 western extremity of the island, this species scarcely 

 attains an inch in height, and specimens from thence 

 were actually described and figured by Withering 

 ("Arrangement of British Plants," 3rd ed. ii p. 282, 

 and pi. xi., fig. 5) as a new species of Gentian, and 

 named by him G. collina." I. H. K. may therefore 

 ■console herself that others before her have been 

 deceived by the same plant at the same place. — Win. 

 Marshall, Ely. 



Side Lights on the Composite. — A most 

 suggestive paper on this subject appears in the last 

 number of the Journal of Botany by Dr. Masters. 

 It is based on a specimen of Helenenium autumnale, 

 in which all the florets appeared stalked and bearing 

 opposite leaves on the stalks, the whole forming a 

 corymb of flowers instead of the ordinary capitulum 

 of a composite. 



British Marine Alg/e — Mr. H. Goole (Ply- 

 mouth) desires us to correct a few mistakes which 

 appeared in his communication on the above subject 

 in our last issue, p. 40. For instance, instead of Dasya 

 puviicea it should be D. punkca ; for Dudrisinia 

 dudrisnagra there should have been Dudresnaia 

 dudresnao-ia. 



GEOLOGY, 



Important Paper on the Geology of West- 

 ern Scotland. — At a recent meeting of the 

 Geological Society of London, Prof. Judd, F. R.S., 

 read a most important and highly interesting paper 

 on Scottish geology. During the seven years in which 

 he has been engaged in the study of these interesting 

 deposits, the author has been able to prove that not 

 only is the Jurassic system very completely repre- 

 sented in the Western Highlands, but that associated 

 with it are other deposits representing the 

 Carboniferous, Poikilitic (Permian and Trias) and 

 Cretaceous deposits, the existence of which in this 

 area had not hitherto been suspected ; and by piecing 

 together all the fragments of evidence, he is enabled 

 to show that they belong to a great series of forma- 

 tions, of which the total maximum thickness could 

 have been little, if anything, short of a mile. The 

 relations of the scattered patches of Mesozoic strata 

 to the older and newer formations respectively, are 

 of the most interesting and often startling character. 

 Sometimes the secondary rocks are found to have been 

 let down by faults, which have placed them, thousands 

 of feet below their original situations, in the midst of 

 more ancient masses of much harder character. 

 More usually they are found to be buried under many 



hundreds, or even thousands, of feet of Tertiary lavas, 

 or are seen to have been caught up and enclosed 

 between great intrusive rock-masses belonging to the 

 same period as the superincumbent volcanic rocks. 

 Occasionally the only evidence which can be obtained 

 concerning them is derived from fragments originally 

 torn from the sides of Tertiary volcanic vents, and 

 now found buried in the ruined cinder-cones which 

 mark the sites of those vents. In some cases the 

 mineral characters of the strata have been greatly 

 altered, while their fossils have been occasionally 

 wholly obliterated by the action of these same igneous 

 forces during Tertiary times. In every case, the 

 survival to the present day of the patches of Secondary 

 rocks can be shown to be due to a combination of 

 most remarkable accidents ; and a study of the dis- 

 tribution of the fragments shows that the formations 

 to which they belong originally covered an area having 

 a length of 120 miles from N. to S., and a breadth 

 of 50 miles from E. to W. But it is impossible to 

 doubt the former continuity of these secondary 

 deposits of the Hebrides with those of Sutherland to 

 the north-east, with those of Antrim to the south, 

 and with those of England to the south-east. From 

 the present positions of the isolated fragments of the 

 Mesozoic rocks, and after a careful study of the 

 causes to which they have owed their escape from 

 total removal by denudation, the author concludes 

 that the greater portion of the British Islands must 

 have once been covered with thousands of feet of 

 secondary deposits. Hence it appears that an 

 enormous amount of denudation has gone on in the 

 Highlands during Tertiary times, and that the 

 present features of the area must have been, speaking 

 geologically, of comparatively recent production- 

 most of them, indeed, appearing to be referable to 

 the Pliocene epoch. The alternation of estuarine 

 with marine conditions, which had, on a former 

 occasion, been proved to constitute so marked a 

 feature in the Jurassic deposits of the Eastern 

 Highlands, is now shown to be almost equally striking 

 in the Western area ; and it is moreover pointed out 

 that the same evidence of the proximity of an old 

 shore-line is exhibited by the series of Cretaceous 

 strata in the West. Although the comparison and 

 correlation of the Secondary strata of the Highlands 

 with those of other areas, and the discussion of the 

 questions of ancient Physical Geography thereby 

 suggested, are reserved for the fourth and concluding 

 part of his memoir, Prof. Judd took the opportunity 

 of making reference to several problems on which 

 the phenomena now described appear to throw im- 

 portant light. In opposition to a recent speculation, 

 which would bring into actual continuity the present 

 bed of the Atlantic and the old Chalk strata of our 

 island, he points to the estuarine strata of the Hebrides, 

 as demonstrating the presence of land in that area 

 during the Cretaceous epoch. He also remarks on 

 the singular agreement of the conditions of deposition 



