6 PRINCIPAL FEATURES 



\\ i stern district, we have a rise northward of 641 feet, to the 

 summit of Mickle Fell; and from Wilton Beacon, the culminating 

 point of the Wolds, there is a rise of 680 feet northward to 

 Burton Head. 



The explanation of these prevalent eastward and southward 

 slopes of the surface is simple; they correspond to the internal 

 structure of the country. In Yorkshire the constituent mineral 

 masses are for the most part stratified*; the strata are not 

 horizontal, but inclined to the eastward, or south-eastward, from 

 an 'axis of elevation ' (PI. II. fig. 2, x) as it is called, or what is 

 in effect equivalent to it, a great line of dislocation (PL II. 

 fig. 1, a/) nearly coincident with the western boundary. The 

 most prevalent slope of the surface then is to the east or south- 

 east, because the rocks upon which it is formed are inclined in 

 that direction (PL II. fig. 1). As the several strata rise toward 

 the west, the surfaces formed on these strata also rise in that 

 direction ; and the surface attains the greatest elevation near the 

 axis of uplifting of the strata. This explanation is fully con- 

 firmed by examining the districts separately. 



In each of the hilly districts, it is toward the northern and 

 western parts that the greatest average elevation is attained; in 

 each the country grows lower toward the east and the south; 

 and upon a view of the whole country, the most prevalent direc- 

 tion of the streams is from the north and west toward the south 

 and east. 



The separate slopes of all the hilly districts to the east follow 

 the inclination of the strata in that direction, and are much more 

 rapid than the average slope of the whole surface : in three of 

 these districts, the north-eastern, south-eastern and south- 

 western, a southward dip of the strata appears along the north- 

 ern edge, and combines with the eastward dip to give them 

 somewhat of the concave or basin-shaped character. The sur- 

 face corresponds to this peculiarity of structure: Holderness 



* Only the 'Whinstone Dike' and 'Whin Sill,' and other small dikes 

 and mineral veins, are exceptions. 



