100 rilOCEEBIXGS OF THE GEOLOGICAL SOCIETY. [Jan. 8, 



indefatigable observers at many points, we are now able to perceive 

 that the districts at present constituting England, Northern France, 

 and Western Germany were included during the Jurassic and Neo- 

 comian periods within a single marine province, the very uniform 

 succession of life in which has been clearly traced. Thus a palseon- 

 tological scale has been constructed which, with due precautions, 

 may be safely used for the determination of the age of any isolated 

 rock-masses which were deposited within the limits of this old ma- 

 rine province. Further, the relations of the different strata and the 

 conditions under which they were deposited at various points have 

 been so far investigated that some progress has been made in de- 

 termining the boundaries of the several gulfs, channels, and islands 

 of that great sea and archipelago which constituted this life-pro- 

 vince. This, in turn, has led to the recognition and study of the 

 minor pala?ontological features which characterized the several sub- 

 divisions of that sea, and, in a much less degree (owing to the paucity 

 of the evidence), of the several land-areas which bounded them. 



Lastly, a considerable amount of knowledge has been gained of 

 the succession of the movements of upheaval and subsidence by 

 which the boundaries of the sea and land within this area were at 

 different periods modified. 



To the interesting patches of Jurassic strata in the Highlands of 

 Scotland, then, we resort, and, in spite of the fragmentary character 

 of the evidence in many instances, seek in them for the solution of 

 many problems of the highest geological interest, among which we 

 may especially instance the following : — 



(1) The determination of the northern limits of the old life-pro- 

 vince to which we have referred, and the question whether the 

 Scotch deposits were formed within it. 



(2) The special palasontological features of the province or sub- 

 division of a province to which these strata belong. 



(3) The conditions under which the various beds constituting the 

 Mesozoic series in Scotland were deposited. 



(4) The influence of climate in affecting the modes of deposition, 

 and consequent character, of the rocks, and also in modifying the 

 palosontological features of the area. 



(5) The position and extent, with the nature and productions, of 

 the lands bounding this portion of the old Hesozoic sea. 



(6) The character and succession of the subterranean movements 

 which affected the area during the Jurassic and subsequent epochs. 



On each of these problems the study of the Highland strata throw3 

 important light ; and to some of them it affords satisfactory and com- 

 plete solutions. That in a case like the present, where the rocks 

 preserved and exposed are of such a fragmentary character, some 

 unfortunate gaps in the evidence will have to be lamented, is of 

 course no more than might be anticipated ; yet I hope to be able 

 to show in the sequel that, by a careful examination, with the 

 aid of the paheontological key, of every trace of these rocks left to 

 us, the cases of total hiatus in the evidence are reduced to a remark- 

 ably small number, and that we are, in fact, able to sketch with 



