HARDWICKE'S SCIENCE-GOSSIP. 



73 



WHAT THE PIECE OF JET HAD TO SAY! 



By JOHN E. TAYLOR, E.G.S., etc. 



OW few of the beau- 

 ties, whose delicate 

 ears, Leaving bo- 

 soms, and supple 

 wrists I am made 

 to adorn, are ac- 

 quainted with the 

 faintest outline of 

 my history and ex- 

 perience ! Not tbat 

 I can esteem it my especial 

 privilege to be considered 

 above other common-place ob- 

 jects in this respect, for many 

 others have a biography quite 

 as romantic as my own. But 

 I will leave it to my hearers 

 to say whether my story is not 

 worth listening to. 



The period when I was born, 

 and in whose rocks I am most 

 commonly found, is that known 

 to geologists by the uame of 

 the Lias. In the lignite por- 

 tion of its strata, among the 

 "Alum Shales," I occur iu 

 my natural state as lumps and nodules. When 

 purest, I am deemed most valuable, on accouut 

 of my use in the mauufacture of the well-known 

 jet ornaments. I am purely of vegetable origin — 

 as much so as coal itself— although I am usually 

 considered a species of " black amber." Like 

 the yellow variety which goes by that name, I am 

 electric when brisldy rubbed. As a fossil pitch 

 or gum, I am related to the peculiar coniferous 

 flora which grew so abundantly, although in com- 

 paratively few species, during the Liassic epoch. 

 The chief features of these vegetable forms I shall 

 presently endeavour to describe to the best of my 

 recollection. 



Eirst let me say a word as to the rock formation 

 in which I am found. Why it is called the " Lias " 

 No. 76. 



few wise men know, so that I may be excused, 

 seeing this uame was given to it so many centuries 

 after my birth. It is usually regarded as a corrup- 

 tion of the word " layers," and I think this is very 

 probable, as the general appearance of the strata is 

 such as to cause such a name to be given to them 

 par parenthese. Thin bands of dark limestone 

 alternate with equally thin bands of dark shale, like 

 so many sandwiches ; this " ribbon-like " arrange- 

 ment is very persistent, at least iu England, and 

 from it may have come the name. The modern 

 science of geology includes, in its technical list, 

 many names which had a humble origin among 

 quarrymen and miners. However that may be, I 

 well remember the alternate stages of quiet aud 

 disturbance which affected the sea near which I was 

 born. Sometimes its waters would remain calm 

 and clear for years, during which colonies of shell- 

 fish or corals would grow over its bottom, and their 

 accumulated remains form a bed of limestone. And 

 then the waters were thick and turbid with mud, 

 which gradually settled to the bottom, lying on the 

 top of the shell bed, and now appearing as a layer 

 of shale. In fact, the alternation I have spoken of 

 is itself a proof of the physical conditions which 

 affected the Liassic sea. The thickness of the 

 various strata is nothing like so great as that of the 

 older formations, although the fossil remains are far 

 more numerous, both in species and individuals. 

 In the " struggle for life," which had been per- 

 petually going on since the first appearance of life 

 in the Laurentian epoch, many new forms had been 

 developed. The total thickness of the Lias is only 

 eleven hundred feet, and this is usually separated 

 into three divisions, termed respectively the Upper, 

 Middle, and Lower. The upper portion consists 

 chiefly of clays, whilst the middle is composed of 

 " marlstone," crowded with fossils. This is remark- 

 able for its containing iron-ore in such abundance 

 as to be worked for that valuable metal in some 

 localities. The Lower Lias is that most characterized 

 by partings oi snale and limestone, already men- 



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