ARHAN. ALLUVIA. 337 



the decomposition of the secondary strata beneath ; inter- 

 spersed with occasional fragments of the syenitic and 

 trap rocks which lie higher up in the island. Except 

 these rare fragments, they bear no marks of foreign or 

 distant transportation. There are no traces of water 

 courses to account for their present position and depth, 

 nor do the form and situation of this range of land, 

 skirting a wide and open sea, or the other circumstances 

 in the condition of Arran, render it probable that they 

 were deposited by diluvian causes. Parallel circumstances 

 however occur in the neighbouring peninsula of Cantyre, 

 which throw light on the subject ; while they also present 

 a series of facts interesting in another manner, as serving 

 to establish a connexion once more general among the 

 several tracts of sandstone visible in these islands and 

 on the adjoining continental shores. On many parts of 

 this peninsula, portions of red sandstone are to be seen 

 detached from those immediately adjoining, occasionally 

 insulated at a great distance from any similar rock, and 

 occupying very minute spaces. Independently of these 

 fragments of sandstone strata, alluvial deposits of a re4 

 colour are also found in j^e same tract ; being most 

 numerous in the neighbourhood of Campbeltown, whence 

 they extend interruptedly to the north of the alluvial 

 plain which lies near that town, and along the western 

 shore as far as Tyanloan. 



These alluvia all consist of red clay and sand with 

 occasional fragments of red sandstone interspersed, and 

 they are disposed in the form of detached banks or low 

 hillocks, insulated from the surrounding land, and easily 

 distinguished by their outlines. They vary in depth from 

 four or five feet to sixty or seventy ; opportunities for 

 examining their sections occurring in many places where 

 they are cut through by the streams from the hills. Where 

 these sections are sufficiently deep, it is evident that they 

 lie on masses of red sandstone ; and in searching for the 

 common line of separation, it is also perceptible that there 



VOL, II. Z 



