332 



MOUNTAIN ASH 



MOUNTAINS 



Illinois reaches a height of 90 feet, and measures 

 TOO by 500 feet at the base; and another in 

 Mi"i~-i|.|.i is 000 by 400 feet, and its topmost 

 mound IK 80 feet above the base. To these must 

 be added the curious mounds constructed in the 

 shape of animals, and sometime* extending to 

 a length of 400 feet. They are must numerous in 

 \\ isconsin, but one of the most interesting i- the 

 serpent mouiul near Im-h Creek, < liiio (figured 

 anil deacribed in The Century, April l!Ki). 



As to the identity iif tin- Mound Imilder* opinions, 

 of course, differ. The general tendency is t.i lecognise 

 their descendants in the Natchez atiii oilier kindred 

 tribes whom the SiMiniaid.s found on the Mis>L .ippi, 

 partly because their chief was both king and 

 di-ity he was reganled as the child of the fiun 

 and so we lind evidences of the religious feeling 

 and the despotic power necessary to secure the 

 accomplishment of such enormous works. The 

 race may |>erha|>s also have survived in the more 

 highly civilis,-d trilx-s whom De Soto and his fol- 

 lowers met with in Florida and the other southern 

 si. ues. lint a comparison of the Moutul linildcrs' 

 civilisation with that which prevailed in Mexico 

 when Cortes landed, supplies very strong argu- 

 ment* for connecting these northern Indians, 

 driven south by their nomadic enemies, with the 

 tribes who came from the north and in turn 

 ex|>elled successively the Toltecs and one another, 

 Mending their more savage customs with the higher 

 civilisation whieh they found there (see MEXICO). 

 The contents of the mounds Bii|>|>ort this view. It 

 i evident that the Mound Builders, like the later 

 Mexican tribe*, wen- in the transition stage between 

 the stone and metal age ; copjicr they had obtained 

 in the same primitive manner as it was obtained 

 in Mexico, but the weapons and tools were stone 

 implement)*, and knives of olisidian especially the 

 well-known sacrilicial knives of the Aztecs were 

 common. Their art and manufactures were both 

 of a low standard ; but it is well known that 

 the invaders of the Mexican tableland partly 

 alworlied the civilisation they found there, partly 

 degraded it. Finally, it may be mentioned that 

 tln> sepulchral mounds yield many evidences of the 

 cruel rites of their builders ; and the pyramidal 

 form of the ' temple ' mounds is reproduced in the 

 A ifiilli of Mexico. See Sijiiier and Davis, Ancient 

 Monument* of the Mississii,}ii Valley (1848) ; Con- 

 ant's Footprints of Vanished Itacet in the Missit- 

 sitipi Valley; Thruston, Antiquities of Tennessee 

 (1890); Shepherd, Antiquities of Ohio ( 1890) ; and 

 Mooreiiead, Port Ancient, Ohio (1890). 



Mountain Ash. See ROWAN. 



Mountaineering. See ALPINE CLUB. 



Mountain-leather, &c. See AMPIIIBOLB. 



Mountain Meadow. See UANITKS. 



Mountains. Kvery one knows what a moun- 

 tain is, and yet it is hard to give an adequate 

 definition of the term. We may say vaguely that 

 any region the surface of whieh risen with a more or 

 leu steep gradient to a height of 1000 feet or more 

 is a mountain. Mountains differ vastly in form 

 .-.onie assuming pyramidal or conical shapes, others 

 forming ridge, others occurring OH irregular amor- 

 plious masses. Some again stand in more or less 

 imitated |K>sitions, whilst in other coses verv many 

 eiowd together, forming a billowy mass of elevated, 

 ground ; ami yet others, amongst which are the 

 most prominent mountains of the glolie, extend 

 continuously in definite directions as long range* 

 and chains for hundreds or thousands of miles. 

 Notwithstanding this diversity of form and of 

 grouping, all mountains may be classified as (a) 

 mountains of accumulation, ((/) mountains of eleva- 

 tion, (') mountains of circumdcntidation. 



(a) Mountain* of Accumulation. Volcanoes may 



be taken as the type of this class of mountains 

 (li;.-. 1 .!. These arc of course formed by the accumula- 

 tion of igneous materials around the' focus or foci of 



Fig. 1. Volcano ; Mountain of Accumulation. 



eruption. Most volcanoes are more or less conical 

 in shape ; but in the case of those which ha\c U-m 

 long extinct the form has often l>ecn greatly 

 modified by the denuding action of the subaciial 

 agents. Some very ancient ones have been so 

 demolished that frequently all that remains of 

 them are mere stumps, formed of the hard 

 crystalline rocks that plug up the pines or flues 

 through which the igneous materials found a 

 passage to the surface. In former times lava 

 seems often to have welled up along the lines of 

 extensive fissures and Hooded surrounding regions. 

 This happening again and again, vast plateaus 

 have been built up. These are called />/idmns of 

 accumulation. Many of these, however, have since 

 been highly denuded, so that they have now quite 

 a mountainous appearance (lig. 2). As examples 



Fig. 2. Plateau of Accumulation, A B; allowing 

 Mountains of Circuutdenudation (in, m). 



may be mentioned the denuded plateaus of Iceland, 

 the Faroes, Antrim and Mull, Abyssinia, and the 

 I leecan. Of course plateaus of accumulation are 

 not always formed ot ignenu* rocks. Any area of 

 approximately hori/.ontal aqueous strata, were it 

 to be elevated to a height of a thousand feet or 

 so, would form a plateau of the kind, such as the 

 plateau of the Colorado. That plateau is geologi- 

 cally of recent origin, and yet sufficient time has 

 elapsed to allow of profound erosion of its surface. 

 Thus, mountains and plateaus of accumulation 

 often owe many of their present features to the 

 action of denuding agents. 



(6) Mrniiitiiiiit ofJslevation owe their origin to 

 the folding, crumpling, and fracturing of strata 

 that accompany certain great movements of the 

 earth's crust. They are lines of weakness along 

 which the rcx'ks have yielded to excessive lateral 

 compression by folding and doubling up, during 

 the sinking down of the cool outer shell of th 

 glolie upon the more rapidly contracting hot 

 nucleus. The simplest structure presented by such 

 mountains is shown in the Uinta Mountains of 

 \V\oniing and Utah. This is a flattened arch of 

 strata, having a breadth of 50 miles and a length of 

 IflO miles, which bulges up to a height of 5000 or 

 6000 feet alwvc the plains on either side. It shows 

 a broad plateau-like surface which has been deeply 

 eroded. Powell believes that a thickness of 

 3J miles of strata has been denuded from its 

 surface. In the Jura Mountains we have a series 

 of parallel ridges, each ridge coinciding with a 

 symmetrical anticlinal or saddle-backed arrange- 

 ment of strata, while the intervening hollows 

 occupy symmetrical synclinal troughs (fig. 3). 

 The tops of the anticlines are all more or less 

 denuded. In the western part of the same range 

 of mountains the flexures of the strata are mostly 



