TIIK PERMIAN SYSTEM 339 



Ayrshire. In the centre of the Ayrshire coalfield near Mauchline 

 lies a pear-shaped area, occupied by rocks similar to those of 

 Thi'inliill (see Fig. 110), and associated with the volcanic breccias 

 of tliis district are some beds of a purple sandy limestone, but no 

 fossils have been found in them. 



The igneous zone consists of a number of lava-flows which mark 

 successive eruptions, and have probably proceeded from more than 

 one vent, for though they are all of a basic character they vary 

 much in lithological composition. Some of them are basalts, others 

 are magnetite-felspar rocks, while the rock of Mauchline Hill is a 

 picrite composed chiefly of olivine and augite. Magnetite is 

 prevalent in all of them, and its oxidation has given them a red 

 colour, on which account they have been described as " porphyrites." 



Besides these interbedded volcanic rocks there is other evidence 

 of the number and activity of the volcanoes. Outside the existing 

 tracts of Trias the Coal-measures are pierced by numerous large 



Fig. 110. SECTION THROUGH THE PERMIAN BASIN OF AYRSHIRE 



/. Basaltic dyke. d. Red sandstones. 6. Lava-flows. 



e. Volcanic necks. <'. Volcanic tuffs. a. Carboniferous rocks. 



pipes filled with a coarse unstratified agglomerate, and usually 

 appearing at the surface as small rounded hills or hillocks. Some- 

 times the agglomerate includes a core or column of lava, and the 

 coal-seams in their neighbourhood are often charred or altered into 

 columnar coke. There can be little doubt that these columns or 

 necks are some of the vents through which the volcanic materials 

 were ejected. The necks are especially numerous in the Dalrnel- 

 lington coalfield, but they occur also in Renfrewshire and Lanark- 

 shire, piercing the highest Coal-measures in those counties. 



Moray. The only other area where Permian Beds have been 

 recognised is in Moray, one small tract lying to the east of the town 

 of Elgin and another near Cummingstone. The rock is a coarse 

 red false-bedded sandstone, consisting of rounded quartz-grains, and 

 containing sand-worn pebbles ; the total thickness of the beds, 

 according to Mr. D. M. S. Watson, 9 being from 400 to 500 feet. 

 Apparently it was formed in a depression or lake in a wind-swept 

 desert region, for near Elgin it has yielded bones of the character- 

 istic Dicynodont reptiles Gordonia, Elginia, and Geikia. The 

 similar sandstone near Cummingstone has not yielded bones, but 

 shows footprints which closely resemble some at Mansfeld in Notts, 





