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A SKETCH OF GEOLOGICAL TIME, 



By ROBERT LIGHTBODY, Esq., F.G.S. 



Ladies and Gentlemen,— I am directed by our President to address you on 

 some interesting geological subject suitable to the character of the scenery, in the 

 midst of which we are to-day, and I much regret that he has not selected some one 

 much better able to do justice to it than I am. However, I must do the best I 

 can, trusting to your favourable consideration, and I propose to select the subject 

 of Geological Time, as one which may be made obvious to those who examine the 

 various strata of which the earth is composed. 



I hardly know how, or where to commence so vast a subject, — the more so 

 as the ladies in general are not supposed to take much interest in the pursuit of 

 Geology, though I see around me some zealous exceptions, who are not afraid of 

 carrying a hammer, — and using it too. Ladies and Gentlemen, — The science of 

 Geology is second only to that of Astronomy in the vastness of its extent, 

 dealing with immeasurable time, both past and future. To human appreciation 

 this seems to differ little from eternity, for the finite senses of man cannot conceive 

 the infinite either of time or space, and are lost for want of something to rest on. 

 Do not be shocked, I beg of you, when I tell you that though this earth we stand 

 on no doubt had a beginning, yet it is quite impossible to arrive at the slightest 

 idea when the ^Umighty Creator first formed it ; but as far as we can read its 

 records in the various strata under our feet, it must have been millions of ages 

 ago. Not only so, but constant destroying and constant reparation appear to 

 be still going in endless succession, making it equally impossible to estimate 

 its future duration as its beginning. I hardly know at which end of the long series 

 of formations to begin in order to give you some slight idea of the amount of time 

 necessarily required by them ; but perhaps the most intelligible way will be to 

 take the last first and work backwards. 



You must bear in mind that, setting aside the Volcanic and Plutonic rocks, 

 all others, with very trivial exceptions, have evidently been formed under water, 

 either salt or fresh, as is proved by the remains of fish and shell fish, and other 

 inhabitants of water, abundantly found in them. These are consequently called 

 sedimentary formations, and must have been deposited in the same manner that 

 we see stOl going on at the bottom of seas, lakes, rivers, &c., and we know how 

 slowly these are formed from year to year. Examine a piece of the rock about 

 you, and count the number of different layers in an inch, and multiply this 

 by the thickness of the beds, and thus estimate the time occupied in their deposit, 

 and whether you calculate by years, or floods, or even by tides, you will find that 

 they requii-ed years beyond calculation. 



