44 



HAUDWICKE'S SCIENCE-GOSSIP. 



combined action of upheaval of portions of the crust 

 and the heaping-up of volcanic material, the latter in 

 some cases forming volcanic islets of considerable 

 extent. He strongly objected to look npon these 

 breaks, even in the British area, where they are 

 most marked, as evidence of a want of continuity 

 over other and far greater areas, or to admit that 

 even where there was conformity in the rocks 

 at this point, "great intervals of time are indicated, 

 unrepresented by stratified formations." The con- 

 formity found in extensive and widely-separated 

 areas is proof also that a gradual contraction took 

 place of an enormous portion of the crust in the 

 northern hemisphere in Palaeozoic times ; and the 

 breaks at the close of the Lower Silurian and in the 

 Devonian are not indications of an arrest in the 

 general subsidence. After indicating the changes 

 which must have taken place in the climate from the 

 gradual spreading of the water and the evidence to 

 be derived from the consideration of the deposits and 

 the faunas, the author drew ihe following general 

 conclusions : — 1. That the condition of the northern 

 hemisphere at the beginning of Palseozoic time was 

 that of immense continents in the higher latitudes, 

 traversed by mountainous ranges of great height, 

 but with a general inclination of the surface, on the 

 one side (European) to the south-west and south, 

 and on the other side (American) to the south-east 

 and south. 2. That these continents were probably 

 covered, at least in their higher parts, with ice and 

 snow ; and that much loose material had conse- 

 quently accumulated over the plains and deeper parts, 

 ready to be denuded off as each part became sub- 

 merged. This would account for the enormous 

 thickness of conglomerates, with boulders, grits and 

 sandstones, found in the early Cambrian rocks, and 

 also to a certain extent for their barrenness in 

 organic remaius. 3. That the depression over the 

 European and American areas was geueral from at 

 least the latitude of 30° northwards ; that the parts 

 bordering the Atlantic were the first to become sub- 

 merged ; the lower latitudes also before the higher. 

 4. That the depression could not have been less 

 altogether, for the whole of the Palseozoic, than 

 50,000 feet; and that conformable sediments to that 

 extent are found over those parts of the areas first 

 submerged, and which remained undisturbed. That 

 volcanic action was chiefly confined to parts of the 

 regions which became first submerged ; that the 

 immediate cause of these outbursts was the weakness 

 of the pre-Cambrian crust at those parts, from the 

 great depression that had taken place, it being too 

 thin there to resist the pressure from within, and to 

 bear the weight of the superincumbent mass of soft 

 sediment. 5. That the seat of volcanic action at 

 this time was at a depth of probably not less than 25 

 miles, as sediments which were depressed to a depth 

 of from 9 to 10 miles do not indicate that they had 

 been subjected to the effect of any great amount of 



heat, and are free from metamorphosis. 6. That 

 the climate at the early part of Palseozoic time was 

 one of very considerable, if not extreme, cold, and 

 that it became gradually milder after each period of 

 depression. That towards the close of the Palseozoic, 

 in consequence of the elevation of very large areas, 

 and to a great height, the climate became again more 

 rigorous in character. 7. That the various changes 

 which took place over the northern latitudes during 

 Laurentian and Palseozoic times allowed marine and 

 land life to develop any progress in those areas at 

 interrupted periods only ; consequently most of the 

 progressive changes in the life had to take place in 

 more equatorial areas, where the sea-bottom was less 

 disturbed, and where the temperature was more 

 equable. Any imperfection therefore in the Palseon- 

 ^ological record belonging to these early times should 

 be attributed to these and like circumstances ; for 

 whenever an approach to a complete record of any 

 part of the chain is preserved to us, the evidence 

 points unmistakably to an order of development, 

 through a process of evolution from lower to higher 

 grades of life. 



Fossils near London. — Will any reader of 

 Science-Gossip kindly inform me of any localities 

 in the West of London where I could obtain fossils 

 and minerals ?—A. T. R. F. 



NOTES AND QUERIES. 



JlJNIPERUS COMMUNIS IN SURREY, SciENCE- 



Gossip, p. 234. — The Common Juniper varies con- 

 siderably, no doubt, in height, according to circum- 

 stances favourable to its growth or otherwise ; but 

 I well-nigh dropped my spectacles when I read that 

 "near Mickleham, &c, it invariably reaches a con- 

 siderable height, say from 10 to 15 feet." The Cater- 

 ham plant may then undoubtedly be considered 

 a starved or a dwarf condition of/, communis ; yet the 

 plant of Ray, Smith, and others known as Juniperus 

 nanuSyVfhether it really be a distinct species or only an 

 alpine variety, is widely different from the lowland 

 plant altogether, although it is difficult to give very 

 tangible characters to distinguish the two plants ; 

 our North Wales /. nanus is certainly most distinct 

 in appearance from any condition of the common 

 species which I ever met with in the chalk districts 

 of England. One would think a very sheltered 

 situation, and some other unusually favourable con- 

 ditions of soil, &c, must be needful to have made 

 the Common Juniper on the Mickleham downs 

 attain such a growth as 10 or 15 feet in height ! 

 — W. P., Llanclderfel, Oct., 1875. 



Tails of Caterpillars. — I think I can throw a 

 little light on the subject mentioned by your corre- 

 spondent " J. R. S. C." in the October number. 

 A few years ago I reared some larvae of the Puss 

 Moth (Centra vinula), and my astonishment was 

 great to notice that, when spinning their cocoons, 

 they continually emitted a liquid from a large open- 

 ing under the true mouth, the like of which I had 

 never seen in any other larva. This accounts for the 

 fact mentioned, that it is only after the last change 



