GEOLOGY OF THE WESTERN DISTRICTS OF CANADA. 501 
very obscure though not altogether wanting, and it is chiefly remark- 
able as forming the base of the system, and as occupying the entire 
area between the foot of the slope of the mountain and the lake 
shore for the whole distance from the Niagara River to Oakville. 
The second stratum is a bed of very hard light grey quartzose 
sandstone, marked frequently with ferruginous spots, but forming an 
excellent building material, and quarried extensively at Lewiston, 
Hamilton, Dundas and other places. This bed is about fifteen feet 
thick at Queenston, and contains the remains of fuci or sea weeds. I 
have also observed it to be distinctly ripple-marked in some localities. 
Above this for a thickness of about sixty feet occur alternate layers of 
red shale or marl, similar to No. 1, and of sandstone or limestone, 
the former principally near the top of the formation. The harder 
rocks here are particularly rich in organic remains, some in a 
beautiful state of preservation, and all remarkably characteristic of the 
geological epoch to which these formations belong, consisting of 
corals, brachiopods ef various species, tentaculites, encrinites and 
trilobites. Of the trilobites, a remarkable crustacean genus strikingly 
characteristic of the Silurian system all over the world, I have only 
detected a few fragments, but they are sufficiently unequivocal. 
Next in succession is a grey and mottled sandstone about fifteen 
feet thick, forming the upper member of what is called by the New 
York State Geologists the Medina Sandstone group. LEncrinites, 
corals and broken shells prevail in great abundance at the top. Over- 
lying this bed is a band of light green shale five feet thick, turning 
inte clay on exposure to the atmosphere. This stratum forms the 
lower member of the Clinton group of New York, and is remarkable 
as being traceable for vast distances east and west in precisely the 
same relative position, and of identical mineral character. Next in 
order occurs a compact bed of light grey, very hard limestone, about 
sixteen feet in thickness, copiously charged throughout its entire 
mass, but chiefly towards the top with the bivalve shell Pentamerus 
{a genus also found extensively in a corresponding position in the 
Silurian systems of England and Russia) as also with a few species of 
Atrypa, a remarkable coral called Favosites gothlandicus, &c. 
This bed forms the upper member of the Clinton group, and wherever 
it is found is an exceedingly handsome and durable stone for building 
purposes. Owing to its hardness it forms a distinct escarpment 
wherever exposed for any length of time to the weather. Then 
