MULL. GEOLOGY. 



probably some alternations . of the two rocks at the point 

 of change, and it is also not improbable that the sand- 

 stone may exist among the upper parts of the strata 

 already described ; but the distance at which they 

 must be viewed does not permit the distinction to be 

 made.* 



As it would be inconvenient to defer the consideration 

 of this sandstone till the other portions of that rock 

 occurring in Mull are described, I shall now add that 

 it occupies in the cliffs a similar situation to the lime- 

 stone. In proceeding from the eastward it is at first found 

 on the shore, bu{ it gradually rises until at length it termi- 

 nates by a single bed situated between the superior and 

 inferior trap. 



As the characters of this sandstone are similar to those 

 of the analogous strata occurring in Sky and Rasay, it 

 is unnecessary to detail them. It is equally apparent 

 that it here bears the same relation to the calcareous strata 

 as on the north-eastern coast of the former island ; being 

 generally superior, but apparently alternating by a few 

 thin strata at the place of change. If there be any 

 considerable proportion of shale in this part of Mull, it is 

 undistinguishable, from the difficulty of access; but as this 

 substance occurs with the coal of Carsaig in the only 

 point where the strata admit of examination, it is not 

 improbable that it also forms a part of that mass which 

 I have supposed to consist of limestone. 



The characters of the limestone are also analogous to 

 those of the calcareous rocks which occur among the 

 trap of Sky, Muck, and other tracts similarly constituted. 

 Its colours are various tints of grey, sometimes mottled in a 



* Plate XX. fig. 11. This diagram may 'be considered as a repre- 

 sentation of the whole southern shore of Mull from a point north of 

 Duart to the Ross, the objects being all brought into one vertical plane 

 and the relative proportions of the parts so altered as to adapt them to 

 the indispensable size of the plate. The true proportions may be gathered 

 from the Map. 



VOL. I. 00 



