GEN 



[ 188 ] 



G E 



applied to culms bent like the knee ; 

 also to peduncles bent at the joints. 



GE'NESSEE SHALE. One of the Devo- 

 nian rocks of America, it is a black 

 shale, with flagstones and sand- 

 stones. 



GE'NUS. (Lat.) 



1. That which is predicated of 

 many things, as the material or 

 common part of their essence. 



2. A subdivision of any class or 

 order of natural beings, whether of 

 the animal, vegetable, or mineral 

 kingdoms, all agreeing in certain 

 common characters. 



GE'ODE. (^ea^s, from yea, Gr.) A 

 roundish piece of mineral matter, 

 sometimes only an incrustation, 

 generally more or less hollow, 

 usually lined with crystals, or in 

 some cases loose earthy matter. 

 The geodes found in the greensand 

 near Sidmouth, says Mr. Bake well, 

 in his valuable Introduction to 

 Botany, are composed of opaque 

 chert on the outside, and contain 

 within, mammillated concretions of 

 beautiful chalcedony, and occasion- 

 ally perfect minute rock-crystals. 



GEO' GNOSTIC. | Pertaining to a 



GEO'GNOSTICAL. j knowledge of the 

 structure of the earth. 



GEO'GNOSY. (from 7^ and ryz/axm, Gr.) 

 That branch of natural history 

 which treats of the structure of the 

 earth. Werner and his disciples, 

 as well as some of the French geol- 

 ogists, have substituted geognosy 

 for geology, the former derived 

 from 717 and <yvu)<m, the latter from 

 777 and Xo'^yos : for this change no 

 sufficient reason can be asssgned, 

 and it is contrary to the established 

 analogies of language. Nothing 

 can be more unmeaning than the 

 apologies that have been offered for 

 substituting ryi>a)<m, knowledge, for 

 Xo'^o?, reason. By the same rule 

 we ought to change meteorology, 

 physiology, &c., into meteorognosy, 

 physiognosy, &c. Prof. Jukes ad- 

 vocates the retention of the word 



geognosy, and would divide geology 

 into three heads : 1. Geognosy, or 

 the study of the structure of rocks 

 independently of their arrangement 

 into a chronological series, and he 

 would again divide geognosy into 

 lithology, and petrology. 2. Pa- 

 laeontology, and 3, Stromatology. 

 GEO'LOGY. (from 79 and XoVyos, Gr.) 

 Geology may be denned to be that 

 branch of natural history which in- 

 vestigates the successive changes 

 that have taken place in the organic 

 and inorganic kingdoms of nature. 

 It is a science founded in exact 

 observation and careful induction ; 

 it may be termed the physical 

 history of our globe ; it investigates 

 the structure of the planet on which 

 we live, and explains the character 

 and causes of the various changes 

 in the organic and inorganic king- 

 doms of nature. It has been em- 

 phatically termed the sister science 

 of astronomy, ranking, undoubtedly, 

 in the scale of sciences, next to 

 astronomy, from the sublimity of 

 the objects of which it treats. 



Geology is as intimately related 

 to almost all the physical sciences, 

 as is history to the moral. As the 

 historian should, if possible, be at 

 once profoundly acquainted with 

 ethics, politics, jurisprudence, the 

 military art, theology ; in short, 

 with all those branches of know- 

 ledge, whereby any insight into 

 human affairs, or into the moral 

 and intellectual nature of man can 

 be obtained ; so is it desirable that 

 the geologist should be well versed 

 in chemistry, mineralogy, zoology, 

 botany, comparative anatomy; in 

 short, in every branch of science 

 relating to organic and inorganic 

 nature. " It was long," says Sir 

 C. Lyell, " ere the distinct nature 

 and legitimate objects of geology 

 were fully recognised, and it was 

 at first confounded with many other 

 branches of inquiry, just as the 

 limits of history, poetry, and my- 



