EXCURSION VII. 



137 



100 feet broad, occurs. We did not notice a single bed 

 either of porphyry or claystone. Many bouldei-s of granite 

 occur ; northwards they are of the coarse-grained variety, 

 but of both varieties on the South Thundergay and Penrioch 

 shores. A few were estimated at as much as twenty to 

 thirty tons weight. 



As the coast from South Thundergay southward is some- 

 what monotonous, we would recommend the tourist, if the 

 day be clear and steady, and he has had an early start, to 

 diverge inland at South Thundergay, visit the lovely and 

 secluded corrie and tarn, called Corrie-an-Lachan (hollow of 

 the lake), at the north-east of Meall-Biorach, ascend Ben- 

 Bharraiu from the north, pass along its eastern ridge, and 

 descend upon lorsa water-foot, through Glen ScaftigilL He 

 will be delighted with the wild scenery, and will notice many 

 objects of geological interest. 



The terraces already noticed (Art. 18) at the mouth of the 

 lorsa, in front of the Duke of Hamilton's shooting lodge, are 



Fig. 28. 



represented on the annexed woodcut (fig. 28) ; they are the 

 most remarkable in Arran. They are the remains of a 

 vast accumulation of detrital matter which once filled 

 the whole of the deeply-embayed area at the mouth of 

 the river, and was most probably deposited as a terminal 

 moraine to two glaciers, which moulded the sides of 

 Sail-Chalmadale, and united their streams near the head of 

 the bay. The seaward front and inland extension would be 



