570 MULL. GEOLOGY. 



with considerable regularity along the shores of that 

 inlet; but the land being little elevated, the ranges are 

 low. As the interior country is generally well covered 

 with soil in this district, the peculiar characters of the 

 rocks are not readily discovered; but it is easy to see 

 that the terraced forms are less prevalent than in the 

 northern parts of the island, or that the trap has not 

 here the stratified appearance by which it is in that 

 division so strongly characterized. There are indeed 

 few circumstances in the characters of the trap rocks 

 more remarkable than the infinite diversity of disposition 

 which they assume. At times they are massive, irregular, 

 and shapeless, rising into unwieldy mountains, the distant 

 outline of which gives no clue toward the discovery 

 of their composition. In other cases their summits are 

 spiry and rugged, resembling the forms so often assumed 

 by granite ; while occasionally they have that round and 

 flowing outline which has been judged characteristic of 

 the schistose structure, and by which Wales and Cum- 

 berland are distinguished. In other instances they ex- 

 hibit that very remarkable terraced form and scalar 

 outline from which their name has been derived, and 

 which is almost sufficient in itself to justify us in pro- 

 nouncing on their nature even from a distant and 

 general view. This form is found to depend on the 

 stratified position in which they are placed ; and the 

 shores of these islands afford numerous opportunities 

 of observing the very accurate and parallel dispositions 

 of the beds. In other situations, of which examples 

 are no less abundant, they present the appearance of 

 irregular and angular rocks, bearing very little resem- 

 blance either to their own more usual forms, or to the 

 general character of any other class of rocks occurring 

 in this country. The eastern part of this district lying 

 in the vicinity of Achnacraig, produces examples of 

 these undefinable and anomalous shapes. 



As it has been a common opinion among geologists 



