TRANSACTIONS OF THE SECTIONS. 11] 
his subject, and showed that several trachytic veins exist, which will partly account 
not only for the elevation of the land after its submergence beneath the ocean, but 
for the innumerable cracks or joints which are almost universally traceable in the 
anite of these islands. In the direction of the Causeway, which at low water joins 
Taylor's Island to the main land of St. Mary’s, he had detected one such vein or 
dyke about 12 feet wide, and having the granite materially altered in character on 
each side of the erupted matter. To the existence of this dyke he attributed the 
alteration in the character of the granite on Taylor's Island, which exhibits crystals 
of tourmaline, replacing the mica, On the north side of Porthloo Bay likewise he 
had found at low water portions of a porphyritic ridge running parallel with the line 
of coast stretching out to Newford Island about N.W. by W. But by far the most 
interesting relic of igneous action in St. Mary’s is to be found in the Elvan Course in 
Watermill Bay, near New Quay, to the N.E. of the island; and the author fully de- 
scribed it, and gave a detailed account of his theory for explaining the apparent stra~ 
tification of the granite in the immediate neighbourhood, A description of several 
of the most striking groups of the rocks concluded the paper, with some curious 
facts as to the wearing action of the atmosphere and moisture in the direction of the 
joints in the granite, which had preduced some extraordinary configurations, particu- 
larly at the Pulpit rock, the Tooth rock, Giant’s Castle, and in Porth Hellick Bay. 
On the Superficial Deposits of the Valley of the Aire at Leeds. 
By Tuomas P. Tears, F.L.S. 
In 1852 numerous large bones were discovered in the brick-earth nearLeeds, which, 
being taken to Mr. Denny, the able and zealous Curator of the Leeds Philosophical 
and Literary Society, were identified by him as the bones of the Hippopotamus. A 
fine collection of these bones, along with the remains of other mammalia, are now 
preserved in the Museum of this Society in Leeds. 
The geological age of the deposit in which the bones were found became a question 
of great interest; and in the hope of contributing in some degree to its solution, I 
venture to offer the following observations to the British Association. 
I have no hesitation in stating that the Hippopotamus major is the particular species 
found in the valley of the Aire. In this opinion I am confirmed by Mr, Woodward 
of the British Museum, and by Dr. Falconer. Of this animal, the Leeds Museum 
possesses the bones of at least four individuals of different ages and sizes. The 
skeleton of one of these is nearly entire. The vertebree and cranium were found 
lying in their proper relative position, the ribs also, and the bones of the extremities. 
The bones had not the least appearance of being drifted or water-worn. Besides the 
bones of Hippopotamus, the tibia and portion of tusk, and some other bones of an 
elephant were found, but these are not sufficient to determine the specific form of 
elephant. ‘he lower jaw of a gigantic ox, presumed to be the Urus, the jaws and 
horn-cores of smaller oxen, the horns of a large round-antlered deer, of a smaller 
deer, and the bones of a horse were also found in the same deposit. ‘To determine 
the age of this fossiliferous deposit, it is necessary to take a survey of all those 
materials which overlie the outbreak of the coal formation in the Vale of Leeds. 
These may be arranged under three distinct heads, each of which requires separate 
consideration :—Ist. ‘The blue clay, which is the oldest. 2ndly. The yellow clay. 
3rdly. The warp, the newest in order of deposition in which the mammalian remains 
were found. 
1. The Blue Clay.—In many localities is found a clay of a more or less blue colour 
on first being exposed, but becoming brownish or yellowish on exposure to the air. 
Wherever this blue clay is found in the Leeds district, it immediately overlies the out- 
break of the coal formation. It occurs in irregular and isolated patches, often abruptly 
sloping off, and evidently showing that it owes the apparent irregularity of its distri- 
bution to the operation of denuding causes. It is seen in the Vale of Leeds at 140 feet 
above the sea-level ; on the north of the river it is found at various elevations, up to 
the higher lands between the Aire and the Wharfe; for example, at Nether Green, at 
175 feet of sea-level; at Woodhouse Moor, 300 feet; at Adel, 375 feet; at Yeadon 
Colliery, 420 feet. On the south, between the Aire and Calder, it is found at various 
elevations, and at Adwalton is seen at the elevation of 600 feet, 
