MINERALOGY. 



397 



mgnMv. rarity of inhabitants ; the fatigue of travelling beneath 

 ~r"~ p ' a burning sky, and an atmosphere darkened by 



the view of that horizon, which seems for ever to fly 

 from before us ; those lonely trunks of palm-trees, 

 which have all the same aspect, and which we despair 

 of reaching, because they are confounded with other 

 trunks that rise by degree* in the visual horizon ; all 

 these cause* combined, make the steppes appear Cur 

 greater than they are in reality. The planters who in- 

 habit the southern declivity o( the chain of the coast, 

 see the steppes extend toward the sooth, as far as the 

 eye can reach, like an ocean of verdure. They know, 

 that from the Delta of the Oronooko to the province of 

 Varinas, and thence, by traversing the binks of the Me- 

 la and the Guaviare, and the Caguan, they can advance 

 three hundred and eighty leagues in the plains, first 

 from east to west, and then from north-east to south- 

 west beyond the equator, to the foot of the Andes of 

 Pasto. They know, by the accounts of travellers, the 

 Pampas of Buenos Ayres, which are also llanos cover- 

 ed with fine grass, destitute of trees, and filled with 

 oxen and horses become wild. 



, nc i. 26. In mountainous and hilly country, funnel-shaped 



pcd hollows of different sixes are sometimes to be observed. 



io. The smallest kind hare been formed by the (inking of 



rock*, and are peculiar to certain formations. The others 



are circular valleys : a stream or river usually traverses 



them, and disappears by a subterranean canal. Hence 



it happens that these hollow* are sometimes filled with 



water, and at other times dry. The Lake of Cirknitz 



N ' of this kind of valley. 



tr ctu- *T. We obtain very distinct conception of the *ur- 

 i* free of the earth, by comparing together the different 

 inequalities that have been described, and we are much 

 assisted in forming this conception, by attending to the 

 coarse of the water over the earth's surface. We can, 

 by meani of the course of rivers, distinguish great por- 

 tion* of the surface of the earth, which are termed 

 riiitrict* by geographer*. These districts are generally 

 very wide and flat troughs or concavities, in which the 

 main river occupies the lower, and its exit from the 

 concavity the lowest point of tlir district. In good 

 maps we can trace out these district, by drawing lines 

 along the points where the small rivers and rivulets of 

 the district took their rise ; and thus we obtain the 

 boundary of the river district. 



In the Ai* land, river district! form peculiar basons 

 or concavities ; and these Mraetime* form connected 

 sries. They are often contained in the mountain 

 group, but more frequently without them ; but still 

 in the high land. Thus the Vallais, which i conca- 

 vity of this kind, lies between the Alp* of Switzerland 

 and Savoy ; and rhe vicinity of Geneva affords another 

 similar example. The river district of the Rhine form* 

 bason* of this kind, in its course towards the 

 . A* long u it continues in the Alp*, these ba- 

 are inconsiderable ; but they increase in magni- 

 a* soon as it leave* those elevated region*. The 

 n in which the Lake of Constance is situated, may 

 erre as an example. A second bason of the Rhine 

 occur* in Baden, where it is increased by many lateral 

 stream*. It extends from Upper Alsace to Hundsruck, 

 and the vicinity of Mayence ; where the Rhine force* it* 

 way through a narrow rocky passage. The river district 

 of the Danube form* a bason in Swabia, several in Bava- 

 ria, and one in Lower Austria, but it nearly shut up at 

 Presburg, w hieh forms the entrance into the great val- 

 ley of Hungary. At the lower extremity of Tlungary, 

 the river i* again forced to seek its way through a 



narrow rocky channel at Orosova, which is the only Geognosy. 

 opening from Hungary into Wallachia. It now con- > ""Y"'' 

 tinues its course through Wallachia, and at length falls 

 into the Black Sea. We have a continuation of these 

 valleys or basons, although still filled with water, in the 

 Black Sea, Sea of Marmora, and Mediterranean. This 

 latter fact is particularly interesting, as it leads to inter- 

 fating considerations in regard to the former state of such 

 basons or valleys. Bohemia affords another example of 

 this kind. That extensive country is a great circular val- 

 ley, whose bottom inclines towards the only opening of 

 the valley, above Konigstein, through which the river 

 Elbe issues, carry ing with it nearly all the water that falls 

 on Bohemia. Immediately below this narrow rocky out- 

 let, there is another small circular valley, which extends 

 from Konigstein to 1'irna. At Pirna it is nearly closed 

 up, the river forcing its way through a narrow rocky 

 opening, and at length it enters a very beautiful valley, 

 in which the city of Dresden is situated. This valley, 

 is we approach Meissen, which is further down the 

 Elbe, becomes narrow, and the river again Hows through 

 a rocky channel, until it escapes into the low country, 

 through which it winds and traverses the flats of Lower 

 Saxony, and is at length poured into the North Sea at 

 Cuxhavcn. The river Don, in Aberdeenshire, also pas- 

 ses through several circular or inclosed valleys, in its 

 course to the ocean. At its estuary, the rocks confine 

 it to a narrow channel ; but on ascending on it for about 

 a mile, the hills recede from it, so as to form a consi- 

 derable extent of country on each side. About Inver- 

 ury it again appears to flow through a channel ; and 

 still farther up it flows through another spacious val- 

 ley. This valley continues for a considerable ex- 

 tent ; it at length contracts, and the river flows through 

 another rocky channel. It continues in this channel 

 for a considerable distance, until it again flows through 

 another wide valley. 



In the county of Dumfries there are appearances of 

 the same kind, as in the course of the Nith, in which 

 we have the vai: < oseburn, and Dum- 



fries; *\vt in other parts ot'Scotl. I 



ilar appearances are to be observed in almost 

 every quarter of the globe; and many of the lake* we 

 see so abundantly distributed over the surface of the 

 globe, are to be considered as similar basons, but filled 

 with water. 



28. Having in the preceding sections described the Dcripiion 

 various inequalities observable on that portion of the of the hot- 

 surface of the globe which is elevated above the level lom of lhc 

 of the sea, we may now give a short description of the *** 

 inequalities discoverable on the bottom of Ike tea, or that 

 part of the globe which is still covered with water. 



From the observations of mariners, we learn that the 

 bottom of the sea ha* very considerable inequalities, 

 and that these correspond, in many re.p-. rt-, to those 

 observed on the surface of the land. Indeed this must 

 be the case, when we consider that the present dry land 

 was formerly the bottom of the &ea. 1 n paragraph fi. 

 we mentioned, that it doe* not present so great a va- 

 riety, or so beautiful a system of elevation* and depres- 

 sions as the dry land ; and this difference is also easily 

 explained. The submarine land must l>e exposed, for 

 many ages, to the action of the waves of the ocean, and 

 of rain, rivers, and lakes, before its surface can agree, 

 in all its features, with that of the dry land. 



When the ground at the bottom of the sea approach- 

 es near to the surface of the water, and is pretty level, 

 it is denominated a shoal. The Dogger Bank, in the 

 North Sea, is an example of the shoal surface. It re- 



