186 GEOLCKJY. 



and architect ; and discloses a variety of indications highly 

 useful in their respective pursuits : to the mincr^ the rocks 

 containing metallic veins and coals ; to the engineer, tjie 

 association of hard rocks with soft ; to the drainer, the 

 intersection of a country by hard dykes, or veins imper- 

 vious to water ; to the farmer, the best places for finding 

 lime-stone, marl, and clay ; and to the arcliilect, the most 

 durable stones for buildings. The person who is attached 

 to .geological inquiries, can scarcely ever want objects of em- 

 ployment and of interest. The ground on which he tread.^ 

 — the country which surrounds him — and even the rocks 

 and stones, removed from their natural position by art, are 

 all capable of affording some degree of amusement. Every 

 new mine or quarry that is opened, every new surface of the 

 earth that is laid bare, and every new country that is disco- 

 veretl, offers to him novel sources of information. In tra- 

 velling, he is interested in a pursuit which must constantly 

 preserve the mind awake to the scenes presented to it ; and 

 the beauty, tlie majesty, and the sublimity of the great forms 

 of nature, oiust necessarily be enhanced by the contempla- 

 tion of their order, their mutual dependence, and their con- 

 nexion as a w hole. 



QuEsTiO.vs. — 1. What ig geology ? 2. What is said of the discove- 

 ries ofcliein'sts nnd mineralogists? 3. Why is the science of geolo- 

 gy important in a practical point of view ? 4. What are the advan- 

 tages of studying geology ? 



LESSON 84. 



Geology. 



Stratifica'tion, the division of a mass of rock into many parallel 

 portions, whose length and breadth greatly exceed t.heir thick- 

 ness.. 



The surface of the globe, considered with relation to its 

 inequalities, is divided into highland, lowland, and the bot- 

 tom of the sea. The highland comprises alpine land, com- 

 posed of mountain groups or series of mountain chains ; 

 mountain chains, formed by a series of those still more simple 

 inequalities, called mountains: in the former we consider 

 tlieir length, height, form, and connexion ; the parts of the 



