394 THE FOSSILIFEROUS 
mentary and incomplete, must be regarded as possessing a cer- 
tain interest of its own, in its character as a portion of the fos- 
sil records of a country whose later geologic history, like her 
civil one both late and early, is meagre in its authentic materi- 
als, and, in consequence, unsatisfactory in its details. 
With but one baiting place,—that furnished by his Grace 
the Duke of Argyle’s discovery of Miocene leaf-beds in the 
Island of Mull,— we have to stride, in Scotland, wholly across 
the Tertiary divisions, and find our first footing on the deposits 
of the Pleistocene. I have not yet seen the leaf-beds repre- 
sented in any collection, save the great British one in Jermyn 
Street. They must, however, be regarded as possessing pecu- 
liarly a Scotch interest, not merely from the glimpse which 
they yield us of those old dicotyledonous forests of our country 
which succeeded, after the lapse of unreckoned ages, the conif- 
erous forests of the Oolite, but also from the circumstance of 
their irrefragably demonstrating that, up till a comparatively 
late period, Scotland had its great outbursts of Trap. <A thick 
bed of rudely columnar basalt overlies the most modern of 
these beds; and deposits of trap tuff, in which his Grace 
detected rolled chalk flints, overlie the older ones; thus show- 
ing, that long after the times of the Chalk, and when trees 
allied to the yew, the plane, and the buckthorn, grew in our 
forests, those deluges of molten matter from the abyss which 
had obtained throughout the earlier geologic ages, had not yet 
ceased, but were, on the contrary, potent enough to overspread 
wide areas to the depth of from twenty to forty feet. From 
these times of fire we at once pass, in this northern part of the 
island, to a period of ice,— to the ages represented by grooved 
and polished surfaces, travelled rocks, boreal shells, and the 
boulder clay. Though geologically the period was one, it 
yields, I am disposed to think, evidence of three distinct suc- 
cessive stages. 
