VIII. 

 THE PARALLEL ROADS OF GLEN ROY* 



HE first published allusion to the Parallel Roads 

 -L of Glen Roy occurs in the appendix to the third 

 volume of Pennant's ' Tour in Scotland/ a work pub- 

 lished in 1776. 'In the face of these hills/ says this 

 writer, ' both sides of the glen, there are three roads at 

 small distances from each other and directly opposite 

 on each side. These roads have been measured in the 

 complete parts of them, and found to be 26 paces of a 

 man 5 feet 10 inches high. The two highest are pretty 

 near each other, about 50 yards, and the lowest double 

 that distance from the nearest to it. They are carried 

 along the sides of the glen with the utmost regularity, 

 nearly as exact as drawn with a line of rule and com- 

 pass.' 



The correct heights of the three roads of Glen Roy 

 are respectively 1150, 1070, and 860 feet above the 

 sea. Hence a vertical distance of 80 feet separates the 

 two highest, while the lowest road is 210 feet below 

 the middle one. 



These 'roads' are usually shelves or terraces formed 

 in the yielding drift which here covers the slopes of the 

 mountains. They are all sensibly horizontal and there- 

 fore parallel. Pennant accepted as reasonable the ex- 

 planation of them given by the country people in his 



* A discourse delivered at the Royal Institution of Great 

 Britain on June 0, 1876. 



205 



