32 Rev. A. Sedgwick and Mr. Murchison on the Geological 



and here ao-ain its lowest beds present the usual character of a fine micaceous 

 compact and slaty sandstone resembling- some varieties of grauwacke. The 

 limestone and associated sandstone rise from the plain of Brodick to the sum- 

 mit of an adjoining- hill, and in their prolongation to the S.W. pass under the 

 trappean and porphyritic masses of the central and southern regions of the 

 island ; whilst towards the coast the same strata are by their range and high 

 inclination carried under the newer conglomerate and red sandstone of Cory- 

 o-ills on the south side of Brodick Bay ; thus affording, in the short distance of 

 about two miles, another exhibition of all the secondary formations previously 

 described. The continuation of the new red sandstone along the southern 

 shores, with the innumerable interruptions in it occasioned by the intrusion 

 of every possible variety of trap rock, does not belong to the immediate ob- 

 iects of this memoir ; but we may remark that this deposit soon loses the cha- 

 racter of a coarse conglomerate, and assuming the aspect of the ordinary new 

 red sandstone is associated with extensive beds of variegated marls, which pro- 

 bably belong to a higher part of that formation than any portion of the con- 

 o-lomerate which overlies the coal-measures to the north of the salt-pans*. 



§ 3. Concluding Remarks founded on the preceding details, S^c. S^c. 



I. It appears from the preceding details, that the principal conclusions we 

 have endeavoured to establish are founded upon the unequivocal order of 

 superposition, and the mineralogical character of the several formations, con- 

 firmed by the nature of the organic remains contained in some of the sub- 

 ordinate beds. 



The lower conglomerate and sandstone are referred to the old red sandstone, 

 because they are inferior to beds which are supposed to represent the car- 

 boniferous order ; because they contain beds having the character of grau- 

 wacke ; and also because they have subordinate beds of concretionary lime- 

 stone resembling the cornstone of Herefordshire and South Wales. 



The central group is referred to the carboniferous order, because it contains 

 beds perfectly like mountain limestone, and having the same suite of fossils, but 



* We are unwilling to mix up our conjectures with a statement of facts founded on perfect evi- 

 dence ; and the structure of the western shores of Arran seems almost to preclude the possibility 

 of deciding upon the age of all the deposits in that quarter. The red sandstone north of Druman. 

 doune, with its veins of pitchstone, &c. is very analogous to that of Corygills. From Tormore 

 to Machrie Water, no strata show themselves in the coast; and it is possible that this wide de- 

 pression may have been occupied by the coal-measures. In this case the highly inclined rocks 

 between Machrie and Eorsa Waters must represent the old red sandstone. 



