The Pyrenees

by Hilaire Belloc

The details of the watershed when they are given in full are of course indefinitely more numerous and complicated, and it may be of advantage for those who would understand the structure of the Pyrenees to glance also at the plan opposite where the dotted line represents the exact trace of the watershed, the dark lines the simple structure described above.

Plan D.

The watershed then should be regarded as the chief feature in the range, and as the backbone of the whole system. Geologically, it is not the foundation of the range. Geologically, the range was piled up by the junction of a number of short separate ranges, each of which ran with a sharper south-eastern dip (about 30°) than does the present long line of saddles which has joined them and forms the existing watershed, and probably the process of the formation of the Pyrenees was upon the model sketched in the following diagram.

But for the purpose of understanding the Pyrenees as they now are, it is the existing watershed which we must consider, and that runs as I have said.

Next, the rule should be laid down that the Pyrenees must be separately considered on their northern and upon their southern slopes. It will be seen later that the physical and historical contrast between the two sides of the mountains is sometimes acute and sometimes slight, but the contrast between the general contour upon either side is such as to make it impossible to unite both in one similar system.

The Northern slope of the Pyrenees is narrow and precipitous. The plains are for the greater part of its length clearly separated from the mountains; the easy country in some places (at St. Girons, for instance, and in the Flats between Lourdes and Tarbes) is not 20 miles as the crow flies from the highest peaks.

On the Spanish side, on the contrary, the mountainous district will run from two to three times that distance. Its extreme width between the open country at the foot of the Sierra Monsech and the Salau Pass is over 60 miles, and it is nowhere less than two days’ good journey on foot from the summits to the plains.

This differentiation between the northern and the southern slopes is not merely one of width, it is due to profound differences in the contours which make the Spanish side of the system a different type of mountain group from the French. For, on the French side the Pyrenees consist in a series of great ribs or buttresses running up from the plains perpendicularly to the main heights of the range, and it is between these ribs or buttresses that the separate and highly distinct valleys which are the characteristic habitations of the French Basques and Béarnais lie. On the Spanish side the main structure is in folds parallel to the watershed; the lateral valleys descending from the watershed run southward for but a very short distance, they come, within a few miles, upon high east-and-west ridges which sometimes rival the main range itself in height and which succeed each other like waves down to the plains of the Ebro. The contrast in structure north and south of the watershed may be expressed in the formula of this plan. A man looking at the Pyrenees from the French towns at their base sees in one complete view a belt of steep rising slopes, and a long fairly even line of summits against the sky. A man looking at the range from the Spanish plains can only in a few rare places so much as catch sight of the main range. In far the greater number of such views he will have before him a high ridge which masques the country beyond. If, then, the reader or the traveller regards the French slope as being essentially a series of profound valleys parallel to each other and running north and south, he will have grasped the main aspect of this side of the range. If he will regard the Spanish slope as a series of parallel outliers which begin quite close to the watershed, and which, though falling at last into the plains of the Ebro, are, even the most southern of them, of considerable height, he will have grasped the structure of the Pyrenees upon the side which looks towards the sun.