568 Notices of Memoir & — 



origin. It is probable that these zones are capable of still further 

 subdivision, but this is not attempted as yet, 



2. From an examination of the relationships of these different 

 zones, the order as given above appears to be an ascending one, 

 proceeding from the margin inwards, the well-marked zone known 

 as the Loch Tay Limestone forming a sort of datum-line, from which 

 one can recognize the positions of the lower and upper schists. 



3. It is supposed that the movements which plicated the rocks of 

 the Highlands were directed from the centre outwards, or from the 

 north-west towards the south-east. This is shown by the fact that 

 where the bedding can be traced the overfolding is generally 

 towards the south-east. Also the foliation, where it has been 

 observed, faces in the same direction. 



4. In the eastern part of the region we suppose that the beds 

 have been folded into a series of isoclines facing the south-east, and 

 that foliation has been developed roughly parallel to the axes of 

 the folds in the bedding, thus making the foliation appear to be 

 roughly coincident with the original planes of stratification. At 

 Comrie, in Perthshire, the axes of the isoclines in the bedding are 

 nearly vertical, but with a slight hade towards the north-west. The 

 axes of the isoclines get gradually lower and lower as we proceed 

 towards Loch Tay. In the same way the foliation planes are nearly 

 vertical along the frontier, but get flatter and flatter as we proceed 

 northwards. 



5. In tracing these rocks towards the south-west an increasing 

 crumpling and folding of the foliation planes, accompanied by more 

 intense metamorphism, is seen to take place : this is made evident 

 in approaching the shores of Loch Katrine and Loch Lomond, but it 

 seems to have reached its maximum in Cowal. 



6. In Cowal, along the Firth of Clyde, the position of the foliation 

 planes has been reversed, now dipping towards the south-east. 

 Between the Firth of Clyde and Loch Fyne the foliation planes 

 have been much crumpled, and still later divisional planes have 

 been developed in them, this being a region of the most intense 

 metamorphism. 



VII. — The Source of Warp in the Humber. By W. H. 

 Wheeler, M.Inst. CE.^ 



IT has frequently been stated that the mud or warp in suspension 

 in the Humber is derived from the erosion of the cliffs on the 

 Yorkshire coast, and the object of the paper is to show that it is 

 physically impossible for the detritus eroded from those cliffs to be 

 carried into the Humber, and that the material in suspension in the 

 water is derived from detritus washed off the land drained by 

 the Humber and its tributaries or eroded fx'om their banks. The 

 drainage basin of the Humber covers 10,500 square miles, and 

 embraces strata of various kinds of rocks, including estuarine 

 deposits, glacial drifts, chalk, sandstone, and oolites. 



The water in the zone extending around the junction of the Trent 

 ^ Read before the British Association, Section C (Geology), Glasgow, Sept., 1901. 



