414 Age of the Tertiary Basalts of the Atlantic. [Dec. 17, 



was so friable, however, that only fragments could be secured. The 

 leaves in the limestone are smaller and very sparsely scattered through 

 it ; there are, moreover, no cleavage planes, and hence much patience 

 is required to obtain and develop them. I have obtained about twenty 

 species of dicotyledon from it, the most prevalent being Grewia crenata, 

 Hr., and Gorylus MacQuarrii, Forbes, and Acer arcticum, Hr., all of 

 which are also found in beds of the same age in Greenland. There 

 are no ferns and only three conifers, a large variety of Guilago adian- 

 toides, Unger, a new Podocarpus, the most northerly species I believe 

 yet found, and Taxus Gampbelli. The fragments from the clays show 

 about eight additional species, and altogether I should judge that both 

 floras were very rich. All the conifers occur also in the shales, and a 

 specimen of Guilago has long been in the collection at Inverary. The 

 most characteristic plan%s of the shales are those described by the 

 Duke of Argyll and Edward Forbes, Platanites aceroides and Rham- 

 nites multinervis. Taxites Gampbelli is not, as affirmed by Heer, 

 identical with Sequoia Langsdorjii, but appears to be a true Taxus. 

 Some other leaves are certainly referable to Protophyllum, and we have 

 representatives apparently of leaves determined as Alnus, Gomus, 

 Berchenia, Populus, and Gorylus — but among them there are none, so 

 far as I can ascertain, that have ever been found in European beds of 

 Miocene age. This is a point, however, upon which I do not wish to 

 insist at present, farther than to say, that the flora seems to bear a 

 prima facie resemblance to cretaceous floras of America rather than to 

 any yet known from Europe. The resemblance of the Coniferse to 

 those indigenous to China at the present day, is too remarkable to be 

 overlooked. 



It has become evident that the fluviatile rocks of the British 

 basalts are of far greater extent and importance than had hitherto 

 been imagined. Before the complete account of them, which I hope 

 later on to prepare, can be proceeded with, their position in the series 

 has to be fixed, their lateral extension to be mapped. 



The first of these points is fortunately not difficult to settle. The 

 base of the basalts is exposed at Burg Head on the opposite side of 

 Loch Scridain, resting upon Jurassic rocks and fragmentary masses of 

 chalk. The base of the series seems formed of two immense sheets 

 of ash, the lowest of which is full of scoriae, and about 100 feet above 

 these, resting upon columnar basalt, in every respect similar to that 

 of Ardtun Head, are fluviatile beds, sands and clays from 9 to 12 feet 

 thick. Overlying these is a bed of rudely columnar basalt, and taking 

 account of all the circumstances, there cannot be much doubt about 

 the fluviatile series on both sides of the loch being upon the same 

 horizon. The beds are, in fact, seen to be horizontal to the west as 

 far as the eye can reach. The horizon of the Ardtun gravels would, 

 therefore, seem to be about 150 feet from the base of the series. 



