AXD GEAVELS OE AEDTTTfT, EJC, EN" HELL. 



279 



though their horizon can always be recognized. As they dip to- 

 wards the sea the gravels again become coarser and are exposed, as 

 pointed out to me by the Duke of Argyll, for short distances under 

 the cliff of rudely columnar basalt ; but no leaves have been found 

 here, and the series is obviously thinning out. 



About 100 feet to the east of the principal ravine the leaf-beds are 

 again well exposed in a path hollowed out by sheep (fig. 5), the sedi- 



Fig. 5. — Section in face of cliff, Ardtun Head, 100 feet east of the 



Ravine. 



a. Basalt. b. G-ravel. c. Leaves. d. Gravel. 



mentary beds continuing to increase in thickness for another 150 feet, 

 when we reach a spot where the Duke's third leaf-bed is beautifully 

 exposed, and where one of his sections was taken (fig. 6). The lowest 

 bed is best worked on the neck of a small jutting headland. Under 

 about 30 feet of gravel (c) we have the black crumbling leaf-bed (c?) 

 exactly as in the ravine * 3 but not the whinstone ; then 7 feet of 

 bedded sand (e), extremely indurated, with very small angular pieces 

 of flint ; followed by 2 feet of partially indurated steel- grey clay (/}, 

 which readily breaks up into rectangular parallelograms, stained 

 almost like tortoise-shell at the partings. Faint impressions of large 

 leaves are visible throughout this. Next we have 6 inches of hard, 

 somewhat laminated, carbonaceous sandstone (g), or rag, with impres- 

 sions of leaves, the most perfect being Ginkgo : passing into 3 inches 

 of the finest-grained, bluish limestone, as fine as that of Solenhofen, 

 and with rare, but extremely beautiful leaf-impressions. These are 

 most difficult to find, and when found, to develop, owing to the 

 conchoidal fracture of the matrix. Only small leaves occur in it, 

 by far the most abundant being Grewia crenulata, Heer. and Alnites ? 

 Macquarrii, Forbes. This is followed by another foot of peculiar 



* It was quarried for the Duke at this spot, but owing to its crumbling 

 nature, with no great success. 



