SPENCER : THE YOREDALE AND MILLSTONE GRIT ROCKS. 387 
In connection with each of these grits is a thin seam of 
coal and underlying seat-earth ; only in one place have we found 
the seat-earth wanting, but in several instances the seat-earth 
occurs without the coal, indicating that the coal had been denuded 
away before the seat-earth was covered up. 
From what we have said about the lenticular character of 
the beds of grit and sandstone, it will be understood that in 
drawing the beds as continuous across the section, and on the same 
horizon, we have only indicated their general average position. 
In places some of the beds of grit and sandstone cannot be seen, 
having either thinned away or are too thickly covered with clay 
or other debris, but as a rule they furnish us with fairly good 
escarpments. 
We have endeavoured in the above estimates to give a correct 
idea of the thickness of each bed of grit and shale from data 
obtained from beds exposed either along the line of the section 
or in its vicinity, and in comparing them with their heights 
above sea level (taken from the Ord. Survey) we know that our 
estimates are tolerably correct. 
Description of Section II. 
SECTION OF THE MILLSTONE GRIT ROCKS FROM WEST TO EAST 
ALONG THE SOUTH SIDE OF THE RIVER CALDER. 
No continuous section of the beds along the lower levels of 
the Calder valley has hitherto been attempted. The numerous 
breaks in the sides of the valley, through which its tributary 
streams join the river, render it a difficult task to make a continuous 
geological section along the banks of the river. At length, after 
much study and research, I have made the attempt, and trust 
that the section will be found to be fairly accurate. 
The section is taken along the south bank of the river and 
as near to it as is compatible with obtaining a continuous section. 
