372 Proceedings of the 



of which the following is an abstract. He stated, that in endeavour- 

 ing to determine the direction of the Pyrenean axis, and its relation 

 both with the direction of the inclined strata, and with the principal 

 parts of which the entire chain is composed, he arrived at the fol- 

 lowing conclusions : 1. That the Pyrenees are not directed from 

 E. S. E. to W. N. W., but at least fifteen degrees southward of this 

 line. 2. That the direction of the strata is rarely parallel to this 

 axis. 3. That the Pyrenees do not constitute a simple chain which 

 may be supposed to have been formed at a single ejection. 4. That 

 they exhibit the traces of various subterraneous evulsions, by which 

 they may be supposed to have been produced. 5. That these evul- 

 sions, which appear to have succeeded each other during the long 

 durations of the ancient periods, were, like those of the Alps, con- 

 tinued into a considerably advanced epoch of the tertiary period. 

 Both Pliny and Ptolemy have fallen into an error, in fixing the western 

 promontory of the Pyrenees at a spot called Aso, which D'Anville 

 supposes to be the Punta de Figuerra, near the mouth of the Bidassoa, 

 and Gmelin the Cape Machicaco ; but neither of these points form 

 the termination of the Pyrenean chain. This chain, to which the 

 promontories in question are mere appendages, leaves them to the 

 north, and extends to the confines of Galicia, as was observed by 

 Strabo. This error has been very universally adopted, and thence 

 the direction of the Pyrenean chain has been usually stated to be 

 from Cape Creus to the Punta de Figuerra, two extreme points ; one 

 of which is situated south, and the other north of the true direction 

 of the Pyrenean axis. This axis really commences in the east, at 

 Cape Cerveres, the crest of which forms the best separation between 

 the torrents directed towards the north, and those directed towards 

 the south. Its western termination is more difficult to decide with 

 certainty, because, on approaching the sea of Galicia, the chain forks 

 out into two branches, one of which terminates at Cape Ortegal, and 

 the other at Cape Finisterre ; a line drawn from Cape Cerveres to 

 the point where the separation takes place, and thence extended to 

 the sea, would terminate between the two capes near Corunna, and 

 the island of Sisarga. This direction, which alone fulfils the con- 

 ditions prescribed for a geographic axis, differs only six or seven 

 degrees from the parallel of the equator. It varies but little from 

 the extreme sinuosities of the crest or ridge, formed by the two 

 declivities of the chain, divides the mountainous region most 

 equally between these two declivities, and most naturally unites the 

 extremities with the centre ; the most remarkable summits with the 

 culminating points, whence proceed the principal fluvial currents, 

 such as the Aude, the Arriege, and the Garonne, in France ; and the 

 Ebro, the Douro, and the Minho, in Spain. A chain may have 

 several geological axes, arising from the direction of special rocks, 

 or other causes ; but these axes must be partial, except where they 

 are, by parallelism, confounded with the central and geographical 

 axis, which is, by its nature, single and universal. A granite axis 



