RECORDS OF EXCURSIONS IN AYRSHIRE. 35 



and commanded much admiration, being perhaps the finest pair 

 of this variety in the kingdom. At the ground they measured, on 

 4th August, 1892, respectively 9 feet 10 inches and 10 feet 2 inches 

 in circumference, and in each case a great number of branches 

 spring immediately from the ground, a feature which has given 

 to this variety the name of fastigiata. 



The chief geological feature, both at the quarries and in the 

 river sections, was the amount of oblique bedding displayed, 

 shewing deposition by strong currents (possibly of wind, rather 

 than water). The great uniformity in the colour of the rock — 

 a warm brick-red — is exceedingly difficult to account for. The 

 conditions of deposit must have been very different from anything 

 we have in this country at the present day, and from what took 

 place in the carboniferous period, before the Mauchline rocks 

 were in existence. Some bits of the sections remind one of what 

 we see in the blown sands of the Ayrshire coast. Even the coarser 

 grained layers are represented in the blown sands, sometimes quite 

 on the tops of the Dunes. The sandstone deposit will occupy 

 about twelve square miles in a pretty compact area, and is 

 surrounded by a ring of volcanic rocks which, we presume, pass 

 under the whole sandstone area, and were thrown out during the 

 earlier part of the Permian period. These consist mostly of 

 porphyrites and amygdaloids, generally speaking, remarkable for 

 the rapid way in which they disintegrate as seen in recent cuttings 

 through them, such as near Tarbolton Station, where the sides of 

 the recently made railway cutting are already in a crumbling 

 state ; and in natural sections cut through them by the Ayr and 

 Lugar Waters at Ballochmyle, near Stair, and on the Auchinleck 

 Estate. The amygdaloids differ greatly from the carboniferous 

 ones by the large amount of saponitic material they contain, and 

 some of them, when polished, have almost as soapy a feeling as 

 some varieties of soapstone. That the volcanoes of the district 

 were active in a certain degree during the deposition of part of 

 the red sandstone, is shewn by the occasional bombs in that rock, 

 several specimens of which may be inspected in situ in the railway 

 cutting near the Mauchline end of the Mossgiel tunnel ; and at 

 the other end of the tunnel the vent of an old Permian volcano is 

 seen in section in the railway cutting. In a pit sinking through 

 these strata a limestone bed was encountered, specimens of which 



