ORIGIN AND AGE OF THE SUNS HEAT. 2G9 



many places from the surface of the country in North 

 Wales. 



The fault which passes along the east side of the 

 Pentlands is estimated to have a throw of upwards of 

 3000 feet * Along the flank of the Grampians a great 

 fault runs from the North Sea at Stonehaven to the 

 estuary of the Clyde, throwing the Old Red Sandstone 

 on end sometimes for a distance of 2 miles from the 

 line of dislocation. The amount of the displacement, 

 Prof. Geikie-f" concludes, must be in some places not less 

 than 5000 feet, as indicated by the position of occasional 

 outlyers of conglomerate on the Highland side of the 

 fault. 



The o-reat fault crossing Scotland from near Dunbar 

 to the Ayrshire coast, and which separates the Silurians 

 of the South of Scotland from the Old Red Sandstone 

 and Carboniferous tracts of the North, has been found, 

 by Mr. B. N. Peach, of the Geological Survey, J to have 

 in some places a throw of fully 15,000 feet. This 

 great dislocation is older than the Carboniferous period, 

 as is shown by the entire absence of any Old Red 

 Sandstone on the south side of the fault, and by the 

 occurrence of the Carboniferous Limestone and Coal- 

 measures lying directly on the Silurian rocks. We 

 obtain here some idea of the enormous amount of 

 denudation which must have taken place during a 

 comparatively limited geological epoch. So vast a 

 thickness of Old Red Sandstone could not, as Mr. Peach 

 remarks, "have ended originally where the fault now 

 is, but must have swept southwards over the Lower 

 Silurian uplands. Yet these thousands of feet of 

 sandstones, conglomerates, lavas, and tutis were so 



* Memoir to sheet 32, Geol. Survey Map of Scotland. 



f " Nature," vol. xiii., p. 390. 



% Explanation to Sheet 15, Geol. Survey Map of Scotland. 



