206 



HARDWJCKE'S SCIENCE-GOSSIP. 



IS kpt. 1, 1S70. 



agency of overlying rock-masses, which originated 

 the former, by their pressing weight caused the latter, 

 when disturbed, to assume the wrinkled, fantastic 

 shapes they now present ! 



It is not long since the Cambrian formation was 

 deemed the oldest in the world ; even its most 

 learned and indefatigable observer called it the 

 Protozoic, imagining its organic remains to be the 

 " first life-forms." This provisional place of honour, 

 however, has since been bestowed on a still older, 

 and of course even more contorted and metamor- 

 phosed a class of rocks, termed Laurentian. 

 "Whether this in its turn will have to give place to 

 one older still I cannot tell ; but this I know, that 

 the more you study the rocks and their contained 

 fossils in the field, the more will you be convinced 

 of the enormous antiquity of the earth, and of the 

 incalculable period during which life has been 

 divinely manifested upon it ! Human arithmetic 

 will never be able to compute my own age, and 

 therefore the very attempt would be futile. Seeing 

 that we slate rocks are, as far as England is con- 

 cerned, the oldest known, who can wonder we 

 should be found in such a dislocated and contorted 

 condition ? Have we not had to bear the heat and 

 burden of the day ? All the rocks of later date have 

 been uplifted into dry land from the sea-bottoms 

 on which they were formed ; and seeing we were 

 older, it was impossible to elevate them without 

 also raising us at the same time ; so that the alter- 

 nate elevations and depressions to which we have 

 been subjected are innumerable. Meantime the 

 overlying formations have been slowly eaten away, 

 attacked either by atmospherical forces or by 

 marine denudation. 



Ear distant though the period of my birth may be, 

 I have a lively recollection thereof. 1 am well pro- 

 vided with "hints to memory," in the shape of fos- 

 sils impressed on, or included in, my parent bulk. I 

 have only to turn to these, and immediately the 

 old life-scene vividly recurs to me. What a strange 

 time it was, and how different to anything I have 

 siuce beheld ! I can readily understand how the 

 earlier geologists should reverently regard our fos- 

 sils as the first created. In them Nature seems 

 almost to have " tried her prentis han' ; " for these 

 earlier organisms bear about them the impress of a 

 lowlier fauna. Not that any are found which cannot 

 be referred to existing natural-history orders, for 

 Nature, like her Lord, knows "no vaiiableness or 

 shadow of turning." Her plan has been to fill up 

 the outline, and this has slowly been consummating 

 during the unknown ages which have elapsed since 

 the Cambrian period. Hence it is that the further 

 you go back in time, the more simple is the fades, 

 or general appearance, both of animals and plants. 

 It is possible that, at the time I was born, the dry 

 hind was sparsely covered with a humble flora ; but 

 it will be evident that as I am of purely marine 



origin, I cannot speak with certainty of what took 

 place elsewhere. I have a dim recollection, how- 

 ever, of certain obscure mosses, lichens, and perhaps 

 reeds, but nothing more certain. That there was 

 dry land, and that this dry land was watered by ex- 

 tensive rivers, I have not the slightest doubt. Other- 

 wise, where would the materials have been derived 

 which make up the bulk of my parent formation ? 

 And, that this material was slowly, and not rapidly 

 obtained, you yourselves may easily see from the 

 fineness of the particles which enter into my com- 

 position. Time again ! Eor the Cambrian formation 

 is no less than eigteen thousand feet in thickness ! 

 and, with the exception of certain beds in the mid- 

 dle of this immense bulk (called by geologists 

 respectively Harlech grits and Lingula flags), the 

 rocks of this period are principally fine-grained 

 slates. Even the grit-stones aud flag-stones afore- 

 mentioned are not of a very coarse texture, but 

 equally attest to the slowness of deposition. 1 

 believe the whole of this formation was deposited 

 in tolerably shallow water, not near so deep as 

 the present Atlantic. You perhaps ask how 

 it was, then, that the strata of a formation nearly 

 three and a half miles in thickness could be depo- 

 sited in only a tolerably shallow sea ? The question 

 is natural enough, and I reply by stating that 

 whilst these strata were slowly forming, the sea- 

 bottom was as slowly subsiding. Hence it remained 

 at almost the same depth during the long period 

 when these fine muds were thrown down. You will 

 find this verified by the fact that in the Lower Cam- 

 brian (in a group called the Longmynds) the tracks, 

 holes, &c, of marine worms (termed Arencolites) 

 are found distributed through a vertical thickness 

 of over a mile of rock. Nor are these humble 

 organic remains scarce ; they occur in countless 

 myriads. After the deposition of the Lower Cambrian 

 rocks, as far as I can recollect, the sea began to get 

 deeper; the deposits formed along its bottom did 

 not quite equal the rate of depression, and so the 

 depth of water increased; but before then 1 well 

 remember how comparatively shallow the sea was. 

 This is attested not only by the countless fossil 

 worms which have won a geological immortality 

 from the trails they left on these early sea-bottoms; 

 but also from the ripple-marks which equally cha- 

 racterize the same set of strata. Nay, we have even 

 evidence of extensive mud-flats, for many of the 

 beds are pitted with rain-drops, and marked with 

 sun-cracks. Thus, far back as English geology can 

 take you, you have evidence of exactly the same 

 kind of meteorological agencies as those which now 

 regulate the physical well-being of the external 

 globe. Cloud and sunshine are testified to by these 

 sun-cracks and ripple-marks. Vapours were raised 

 of solar heat then as now, and the bow was set in 

 the cloud, although not as yet selected as a cove- 

 nant to man. 



