58 report — 1865. 



those described by Prof. Sedgwick as occurring to the north of Ulverston (Aberdeen 

 Meeting of the British Association), and the result of these faults causes these rocks 

 to occupy a large area in the south-east portion of the Lake country. These rocks 

 in some localities aflbrd fossils, and the fossils refer them to the Caradoc age. The 

 Caradoc rocks in the north-west of England are therefore referable to three groups, 

 namely, a lower group consisting of ash-beds and porphyries, a middle series made 

 up of limestones with shales (Coniston limestones), and an upper group composed 

 of grey, flaggy, and gritty rocks (the Coniston flags and grits). In the Lake 

 district there are no equivalents of the Middle Silurians, the Llandovery group, as 

 no traces have been detected of the smooth Pentameri, of Atrypa hemispherica, or of 

 any other characteristic fossils of this portion of the Silurian system. The rocks in 

 the neighbourhood of Kendal, from the nature of their fossil contents, are distinctly 

 of the Ludlow age, and it does not appear that in the Lake country any portion of 

 the Silurians are exhibited which lie between the Caradoc sandstones and the Lud- 

 low group. 



Besides the north-east and south-west faults before alluded to, and which are of 

 an ancient date, as they not only do not affect the Upper Old Red Sandstones and 

 the overlying Carboniferous rocks, but have had the irregulari ties resulting from them 

 planed down before the deposition of the Old Bed Sandstones, there is another 

 series of faidts of a later date, which affects the Upper Palaeozoic rocks. Along 

 the lines of these newer faults, which have nearly a north and south direction, the 

 most important of the Lakes occur. They give rise to the prominent north and south 

 ■valleys, and in combination with the older system of faidts, they produce in a great 

 measure that bold and varied outline which gives so much beauty to this portion 

 of the north-west of Eugland. 



On the Silurian Hocks of the Isle of Man. 

 By Prof. Harkxess, F.R.S., F.O.S., and H. Nicholson. 



The largest portion of the Isle of Man is occupied b}' rocks which have hitherto 

 been regarded as appertaining to the metamorphic group. 



These so-called metamorphic rocks form the cliffs and bold coast on the north- 

 west and south-east sides of the island, and in the interior the mountainous portion 

 of the country is composed of them. Exposures of these rocks are well seen on 

 the coasts, but in the mountainous districts soil and peat to a great extent cover up 

 the rocky masses. 



The old rocks of the Isle of Man are not, however, of a metamorphic nature, but 

 consist of dark grey slaty beds, which in some localities assume a coarser nature, 

 and sometimes put on the aspect of quartz rocks. 



These rocks, as they are seeu in the neighbourhood of Douglas, dip south-east, 

 and this dip continues, with some local variations, as seen along the coast, to Moar 

 Creek on the south side of Maughold Head. On the north-west side of Moar 

 Creek directly opposite dips occur, namely, towards the north-west, and in this 

 locality the prominent axis which intersects the older rocks of the Isle of Man, and 

 which has a north-east and south-west course, is seen. On or near the line of this 

 axis, near Maughold Head, veins of haematite occur, which appear to have a direc- 

 tion corresponding with that of the axis. 



The anticlinal axis can be seen on the opposite or south-west side of the island 

 at Port Erin, to the north of which, along the coast, north-west dips prevail, until 

 the older rocks are seen passing under the Old Red Conglomerates in the neigh- 

 bourhood of Peel. South of Port Erin the inclination is towards the south-east, 

 and this inclination obtains, with local exceptions, where the older rocks occur, 

 along the coast to Douglas Bay. 



There are two localities in the Isle of Man where the dark grey slates exhibit 

 strata of a different nature upon them. These are Douglas Head and Bank How. 

 The rocks here have a green colour, are distinctly bedded, and, at Bank How, have 

 porphyries overlying them. These green rocks are conformable upon the dark grey 

 slates. Their line of strike connects those seen at Bank How with those of Douglas 

 Head; and between these two headlands, which form the north-east and south- 

 west boundaries of Douglas Bay, the same rocks are seen forming the reef known 

 as the Conistor rocks, upon which the Tower of Refuge is built. 



