PARALLEL MOUNTAIN CHAINS. 353 



earth's crust, travelling from north to south, have crumpled up the 

 rock masses into parallel ridges running east to west, the slopes of 

 which form the great Eurasian and North African continent ; for the 

 north of Africa, like Europe, has its chief extension from east to west. 



In endeavouring to understand the conformation of Europe, we 

 may begin by noticing the east to west extension of the Cantabrian 

 mountains and Pyrenees. Parallel to these, crossing the tableland of 

 Castile, are the Guadarama mountains, mountains of Toledo, the 

 Sierra Morena, the Sierra Nevada, divided from each other by valleys 

 more or less deep ; while farther south are the chains of the Little 

 and Great Atlas, parted from the Sierra Nevada by a deeper valley 

 which admits the ocean. Turning next to the east of Europe, we 

 find in Asia Minor another tableland, comparable to Spain, bordered 

 to the north by the Caucasus and traversed by parallel ranges, which 

 run east and west. 



We may then perhaps conceive how it has come about that the 

 intermediate Mediterranean region acquired its peculiar contours, 

 owing to downward or synclinal folding, which has not sunk moun- 

 tains out of sight like those east and west, but has prevented them 

 from being formed, by using up the materials of the earth's crust in 

 the production of folds of a different order. Whoever will experiment 

 on the contraction or crumpling of materials on spherical surfaces, 

 will see that, with a predominant anticlinal elevation, an arrangement 

 of primary folds at right angles to the compression is produced, but 

 whenever a moderate synclinal depression is formed on the flank of 

 the main axis of elevation, then lateral chains or spurs are formed, 

 more or less at right angles to the main ridge, but under inverse con- 

 ditions to those in which William Hopkins demonstrated the two 

 orders of fractures dependent upon strain in an anticlinal elevation. 



Between the Caucasus and the Pyrenees lie the whole system of 

 mountain ranges -of the south of Europe, which consists of main chains 

 and spurs. The chain of the Cevennes runs north as though it were 

 a spur dependent u-pon the Pyrenees ; but the mountain axis of the 

 Pyrenees, interrupted for a time by depression in the Gulf of Lions, 

 becomes prolonged into the Mont des Maures in France, and is 

 deflected northward parallel to the Cevennes, forming the Graian 

 and Cottian Alps, before it resumes its main direction east, in the 

 Pennine Alps, the Lepontine Alps, the Eha3tic and Noric Alps, which 

 strike away eastward to the Carpathians. Dependent upon this 

 great range are parallel subordinate ranges ; and spurs are given off to 

 the south and north. It seems to be a characteristic of a spur that 

 an intervening area of depression separates it more or less from the 

 main chain upon which it depends ; for we find not only the chain of 

 Corsica and Sardinia running south from the Gulf of Genoa as a 

 spur from the Atlas or the Alps, but the Apennines extending S.E. 

 from the Alps as the axis of a peninsula which is a secondary con- 

 sequence of the great Alpine elevation. Similarly the Julian and 

 Dinaric Alps, like the northern spurs of the Balkans and the Sieben- 

 biirgeii of eastern Transylvania, run south-east. If the southern 



VOL. i. z 



