94 
degradation of that rock, but a thin layer of the new red sand- 
stone runs immediately upon the back of the upper limestone, 
and is in fact drained by it. Oak trees flourish near Carcroft, 
which they seldom do on the real limestone soil. There is 
also on the east side of Norton, parallel with the river Went, 
a portion of new red sandstone, made very fertile by being 
drained by the limestone. The soils in both places are of 
considerable depth. On the south of the Don from Hex- 
thorpe by Balby and Loversall, to Tickhill, this bed of lime- 
stone is covered, and its soil intermixed with diluvial debris 
which at once alters the texture and quality of the soil, and 
from this cause the lands at Hexthorpe, Balby, Loversall, 
and particularly at Tickhill, afford excellent grazing pastures, 
and the rents at the latter place reach as high as £2 to £2 1 Os. 
per acre. The average rent of the remainder may perhaps be 
stated at 23s. to 25s. per acre. The places at which lime is 
burnt for agricultural purposes are Knottingley, Criddling 
Stubbs, Spring Lodge, and Womersley, and for four miles to 
the south of Knottingley the stone is of superior quality ; but 
in one mile and a half to^ the south of Womersley, magnesia 
enters into the composition of the stone, and it can then be 
used only for making mortar. The magnesian beds, which 
are true dolomites, are easily known without any analysis : 
they are granular and crystalline, and when examined with a 
lens, show a glimmering lustre, and do not exhibit the smooth 
conchoidal fracture. The crystals, if any cells can be found, 
generally exhibit the inverse rhomb, rarely the equiaxe ; but 
where the magnesian disappears the crystals generally lose 
the rhombic form, and exhibit modifications of the dog-tooth 
form. Between Womersley and Tickhill, stone from this 
bed is not at present burnt for agricultural purposes ; but near 
the latter place, though the bed is seventeen feet thick, and 
contains of this six feet six inches of true dolomite, it is yet 
used in the quantity of three chaldrons to the acre, more 
