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Show 190 EMIGRANT'S GUID}~. rising near, does not actually reach the latter form ation. BeyonJ James' river to the southward, the streams flowing into the Ohio, rise upon the border, or in the primitive, and cross the transit ion into the secondary, over which they flow into the main stream. The reader will remark, from the fo re ~ oin g, that the real Jividinct line between the watcri of the Ohio and lVJiss is3ippi rive rs, and thos~ of the Atl antic ocean, is actuaJly uninf1uenced by the mountain3. It is a general, but a very unfounded opiuion, that the Atla ntic declivity* rises from the northwestern shore of that oceau to tbe summit of the Aleghany mountains, and that from that elevation the continent again declines towards the Mississippi. To clearly unJerstand tile physical conformation of any country, two di stinct species of eleva· tion must be noticed ; first, what is properly called mountains, and secondly, hills formed by the gradual sinking of valleys from the abrasion of waters. In common language hi11s and mountains are mere relative terms, to signify more or less elevation ; but, geologica) .. ly, they are not only specifically, but generically di stinct, at least they are so in the United States. The mountains are protuberances rising out of and above the hills, but composed of very different materials, and arranged in a very dif· ferent manner from the latter. Ascending from either the Atlantic ocean or Ohio river, the hills rise gradually tO\vards the separation of the waters ; the mountains on the contrary seem to preserve no regularity in their elevation, as it respects their local di!:itance from the ocean, or rivers of the Ohio valley. Upon the annPxeu map of the Unite? ~t~tes_, is etcbe?, and_ coloured brown, the gre at outline of the MJ!:Stsstppt valley, mcludmg those of the Ohio and Illinois; ;1nd also the two latter spaces, distinguished from the great v<Jlley of which they form minor parts. This will present to the eye more dear definitions of the plJysiognomy of the United States, than can be given by verbal description. 'f.he terms used in this article te distinguish the various rocks, are not m c?m.mon ~se : s,o,me explanation is therefore necessary to eic~ se ~betr 1_nsert10n: 1 here is nothing so necessary iu the commumca~ wn ~.f tnformatwn, as clear terms, having a definite and generally recetved Hlea attached to them. In a science so recent in re(J' ular classification as that of geology, the terms are new to most reaJers, but without them, no real useful knowledge on the su bj ect can be conveyed through the medium of recorded fa cts. Primiti ve, transi· tion, secondary, and alluvial, when once unde rstoou ena ble the mind to seize with certainty the informat ion inteudeu to' be o-iven by the use of these terms. 0 One of the_ most profound geologists that the world h ::~ s produced,t ~as observ~d! m a recent publication, that Hit might have been as l'vell, 1f when gt_vmg n~mes to the different classes of rocks, all reference to th~ relative penod of their origin , or formation. had been avoided; and tn place of primitive, and seconJary, some other names had been "ll S~.e ?ynop~is, page 7, of Geographica1 Introduction. ' . t '"rl.ham M Clure--observatious on the Geology of the United States, PJir· radelplua, 1817. I EMIGRANT'S GUIDE. 191 auoptec1 , taken from the most promise_nt feature, or general property of the class of rocks intended to be desigt~a.ted, such a~, perha~s, crys· t l . · place of primitive and denontwn, or h(,)r'l.zontal, m place (L we Ill ' . .r . d of secondary. But as these old names are m general use, an con-secrated by time and long habit, it is more t~an probable that the present state of our knowledge does not authonze us to cha~ge them. The adoption of new names, on account of some ?ewly d! scovered property in t~e substance, is the cau~e of much_ mcmwemenGe al ready; and it adopted as a precedent m future, wtll create a co~fused accumulation of terms, calculated to retard the progress of the science. When we change the names given to defined substances by. thos: ,who went before us, what right have we to suppose that posterity wilt re-spect our own nomenclature?" The water-tourses falling from the mountain valleys towards t~e Ohio are mostly rapid, and many of them are encumbered wtth catar~cts none of which are of considerable height. The streams of Alegh~ny and Monongt::hela, pass over a co,ntinuation. of rapi~s, without any that deserve the name of Falls . . 1 he Yo~g~wgheny ISi in one place, viz. the passage of Chestnut ndge, prectpttated about seven feet. The great Kenhawa has one considerable and several lesser precipices passing across its bed, producing cataracts. The Cumberland and Tennessee, though rapid in their courses, are, nevertheless navigable almost to their sources. The' rivers of Kentucky are but little impeded with rock in their bed~, but flow through deep chasms, that have been worn out of the calcarious rocks through which those rivers flow. To theN. W. of the river Ohio the whole regwn under review seems to rest upon a secondary base, covered occasionally by a recent alluvion. Limestone and sandstone slate, are the predominant rocks. Rounded pebbles are frequent; often in loose masses, though sometimes forming a crude breccia, or pudding stone. Much of the surface of Illinois territory, states of Indiana and Ohio, are flat, and exh ibit the u.·ual featutes of alluvial countries. Extensive prairies, flat and sometimes swampy, spread over a large extent. The eastern part of the state of Ohio is hilJy, the northern flat, and in its natural state is covered with woods : the northwestern prairie and the centre are diversified. Two works of different characters and merit, have been written upon the valley of Ohio. Mr. Volney wrote from personal observa· tion, but the fruit of his actual experience was injUJ"ed by preconceived sy stem!. Dr. Daniel Drake gave to his work the humble and circumscribed name of a picture of Cincinnati and the Miami country, though, unJer that modest title, it contains more really useful matter respecting the valley of Ohio, than all other works extant. There are two modes of pursuing knowledge ; one, by first forming tlileories, and then searching for facts to establish those theories: the second mode i~ to collect facts, and from those facts to form systems. In their researches, Volney pursueu the former, Dr~ke the latter mode: these authors have respectively succeeded, according to the soundness of their ~paterials and course of their operations. Situated almost in the centre of the valleys of Ohio and Illinois, |