364 



LITERARY AND SCIENTIFIC. 

 WORCESTERSHIRE NATURAL HISTORY SOCIETY. 



On Tuesday evening, Nov. 4th, Edward Morris, Esq. M. R. C. S. resumed 

 his Lecture on Geology, most pleasingly illustrated with a rich display of specimens 

 from the Museum, and drawings on a very large scale, presenting various sections 

 of rocks, and representations of those singular extinct monsters, the ichthyosaurus, 

 and plesiosaurus, which were most kindly painted by a lady con amorey for the 

 gratification of the Society, and the advancement of scientific research. 



" Geology," observed the learned Lecturer, " offers to us boundless opportuni- 

 ties to increase our intellectual stores, and to furnish our minds with new subjects 

 for contemplation; beautifully adorned as is the surface of the earth, still more 

 astonishing and admirable will the earth itself appear, when its structure and 

 history are developed as far as the genius and industry of man have hitherto 

 accomplished that object. That we may embrace the high gratification of contem- 

 plating the earth as a whole, we must first bend our minds to an attentive consider- 

 ation of its several parts. We sometimes meet with difficulties or obstacles in our 

 progress, and fancy the study dry and uninteresting — but geology requires and 

 merits the exercise of the best energies of the mind, and when so pursued, it will be 

 found most engaging." 



The lecturer here gave a condensed recapitulation of his former elaborate lecture 

 upon the primitive rocks, described their varieties, and exhibited specimens, several 

 the fruit of his own researches, among the romantic Malvern chain. In mentioning 

 chlorite slate, he observed, that at the base of one of the most distant hills in the 

 southern Malvern range, a shaft had been sunk by some ardent speculator in search 

 of coal in this rock, tempted doubtless by its dark colour. He had noticed this pit 

 in the course of his geological researches, but had not been able to ascertain the 

 measure of the ardent zeal of this speculator, who had, of course, laboured in vain, 

 the coal beds lying considerably higher in the scale. In fact, it was hardly neces- 

 sary for him to remark, that in this order of rocks, no organic remains, either 

 animal or vegetable, had been ever yet found. He should therefore now direct the 

 attention of his audience to the secondary rocks, give a general sketch of their 

 relative position, make some remarks on their structure, and the probable manner 

 of their formation. 



Chemistry was essential to the geologist in his investigations, for it subjected to its 

 ordeal the rough granite rock and detected its composition, which was absolutely 

 necessary for scientific induction. Thus 100 parts of granite contained 



Silexorsand 70 



Argil or clay 15 



Lime 1 



Potass 7 



Oxyde of iron 3 



and some other substances in small proportions. Hornblende yields a larger pro- 

 portion of lime, and syenite, in which hornblende takes the place of mica, produces 

 eight per cent, of lime, and six per cent, of xiiagnesia. Thus chemistry solved the 

 question as to the source whence these substances forming the secondary rocks were 

 derived, and displayed to our notice a beautiful simplicity in the operations of nature. 

 Limestone, being a principal constituent of the secondary rocks, and generally 

 so well known for its economical uses, the lecturer observed that he should devote 

 some time to its examination. The formation of limestone was to be traced to three 

 distinct operations, chemical, animal, and mechanical. The first operation fell 

 under our daily notice. If a spring of water charged with an excess of carbonic 

 acid, or fixed air, percolate any rock having lime in its composition, a portion of that 

 lime will be dissolved by the water, and thus brought to the surface of the earth as a 

 supercarbonate. On exposure to the air, this solution of lime loses a portion of the 

 carbonic acid ; thus the supercarbonate which was able to hold a large quantity of 

 lime in solution^ becomes a carbonate able to hold but little, and consequently the 



