8 GEOLOGICAL SURVEY OF ALABAMA. 
The highest and most prominent mountains and ridges 
in the Coal Field are the following: first towards the north- 
west is Shade’s Mountain, formed of the lower measures of 
the Millstone grit, and following along the northwest boun- 
dary of the Coal Field from Canoe Creek in St. Clair county, 
to a point three miles west of Scottsville, in Bibb county. 
This ridge, like all the others in the field, changes its name 
with the locality : thus, in Bibb county it is known as Sand 
Mountain ; in the lower end of Shelby county it bears the 
name of Farrington Mountain; it is called Shade’s Moun- 
tain through most of Shelby and Jefferson, and Rocky 
Ridge in St. Clair county. — 
The next ridge to the southeast of Shade’s Mountain, and 
parallel with it almost the whole length of the Coal field 
and formed of the middle portion of the Millstone Grit, bears 
the name of House Mountain in the south end of Shelby 
county, of Pine Ridge in the north end of Shelby and 
south end of Jefferson county, and of Flat Ridge in the 
north end of Jefferson county, while all over St. Clair 
county it is called Blackjack Ridge. 
The next ridge to the southeast of the two just described, 
parallel with them, and formed of the upper ledges of the 
Millstone Grit, is known by the name of Red or Chestnut 
Ridge in Shelby and Jefferson counties, and by the name of 
Grassy Ridge in St. Clair county. 
The mountains formed by the Montevallo conglomerate 
are confined to the lower or south half of the Field; the 
most prominent being Pea Ridge, which is a flat, wide ridge 
extending from Lacey Station on the Brierfield, Blocton 
and Birmingham Railroad to the fork of Big and Little 
Cahaba Rivers. This ridge owes its high altitude to the 
presence of the conglomerate and to the fact that the meas- 
ures are nearly flat. It is the broadest ridge in the field 
and divides the waters of the Big and Little Cahaba Rivers. 
The same conglomerate forms another ridge, a little lower 
in altitude, over the synclinal of the Dry Creek Basin. This 
is much less extended than Pea Ridge, but nearly as high 
as Pea Ridge in its central part. 
In the northern end of the Coal Field, in Haiicn to the 
three prominent ridges of the Millstone Grit already de- 
