Geologic units in Fentress county, Tennessee

Additional scientific data in this geographic area

Rockcastle Conglomerate (Pennsylvanian) at surface, covers 59 % of this area

Conglomeratic sandstone and sandstone, gray to brown, fine- to coarse-grained. Thin coal-bearing shale locally present near middle. Thickness 150 to 220 feet.

Fentress Formation (Pennsylvanian) at surface, covers 11 % of this area

Mostly dark-gray to light-brown shale, with minor siltstone and sandstone. Wilder coal near middle. Laterally equivalent to entire Gizzard Group and all of Crab Orchard Mountains Group below Rockcastle Conglomerate. Thickness as much as 340 feet.

Monteagle Limestone (Mississippian) at surface, covers 7 % of this area

Mainly fragmental and oolitic, light-gray limestone; blocky bryozoan chert weathers from base. Thickness 180 to 300 feet.

Pennington Formation (Mississippian) at surface, covers 6 % of this area

Reddish and greenish shale and siltstone; fine-grained dolomite; dark-gray limestone; and thin-bedded sandstone. Persistent dolomite bed at base. Thickness 150 to 400 feet.

St. Louis Limestone and Warsaw Limestone (Mississippian) at surface, covers 5 % of this area

St. Louis Limestone - Fine-grained, brownish-gray limestone, dolomitic and cherty. Thickness 80 to 160 feet.; and Warsaw Limestone - Mainly medium- to coarse-grained, gray limestone, crossbedded. Includes much calcareous sandstone and shale to the north. Thickness 100 to 130 feet.

Crab Orchard Mountains Group, including Rockcastle Conglomerate, Vandever Formation, Newton Sandstone, Whitwell Shale, and Sewanee Conglomerate (Pennsylvanian) at surface, covers 4 % of this area

Crab Orchard Mountains Group - Conglomerate, sandstone, siltstone, shale, and coal; from top of Rockcastle Conglomerate to base of Sewanee Conglomerate. Thickness 200 to 950 feet; including Rockcastle Conglomerate - Conglomeratic sandstone and sandstone, gray to brown, fine- to coarse-grained. Thin coal-bearing shale locally present near middle. Thickness 150 to 220 feet; Vandever Formation - Mostly shale and siltstone, dark-gray to light-brown; conglomerate or sandstone in middle to south. Lantana and Morgan Springs coals near base and top. Thickness as much as 450 feet, average about 300 feet; Newton Sandstone - Sandstone, gray to brown or pink, fine- to medium-grained, locally conglomeratic. Thickness as much as 200 feet; average about 90 feet; Whitwell Shale - Mostly dark-gray to light-brown shale, with minor siltstone; locally middle part is sandstone. Richland coal near base; Sewanee coal in upper part. Thickness as much as 220 feet, average about 75 feet; Sewanee Conglomerate - Conglomeratic sandstone and sandstone, gray to brown, fine- to coarse-grained. Thickness as much as 200 feet, average about 100 feet.

Bangor Limestone and Hartselle Formation (Mississippian) at surface, covers 4 % of this area

Bangor Limestone - Dark brownish-gray limestone, thick-bedded. Thickness 70 to 400 feet., and Hartselle Formation - Thin-bedded, fine-grained sandstone interbedded with gray shale; with oolitic and coarse-grained limestone beds locally. Thickness 0 to 80 feet.

Crooked Fork Group, including Wartburg Sandstone, Glenmary Shale, Coalfield Sandstone, Burnt Mill Shale, Crossville Sandstone, Dorton Shale (Pennsylvanian) at surface, covers 2 % of this area

Crooked Fork Group - Shale, sandstone, conglomerate, siltstone, and coal; from Poplar Creek coal to top of Rockcastle Conglomerate. Thickness 320 to 455 feet; Wartburg Sandstone - Sandstone, gray to brown, fine- to medium-grained, locally conglomeratic. Poplar Creek coal and thin shale at top. Thickness 0 to 50 feet; Glenmary Shale - Mostly dark-gray to light-brown shale with minor siltstone and sandstone. Thin coal near base locally. Thickness 50 to 150 feet; Coalfield Sandstone - Sandstone, gray to brown, fine- to medium-grained. Thickness 0 to 80 feet; Burnt Mill Shale - Mostly dark-gray to light-brown shale, with minor siltstone. Thin sandstone locally present near base. Hooper coal just above base. Thickness as much as 110 feet; Crossville Sandstone - Sandstone, gray to brown or pink, fine- to medium-grained, thinly and evenly bedded. Thickness 30 to 70 feet; Dorton Shale - Mostly dark-gray to light-brown shale, with minor siltstone and sandstone. Thin coal near top. Rex coal as much as 70 feet above base. Thickness as much as 150 feet.

Fort Payne Formation and Chattanooga Shale (Mississippian) at surface, covers 0.6 % of this area

Fort Payne Formation - Calcareous and dolomitic silicastone; contains bedded chert, cherty limestone, and shale; scattered crinoidal limestone lenses. Thin green shale (Maury) at base. Thickness 100 to 275 feet.; and Chattanooga Shale - Black carbonaceous shale, fissile. Thickness 20 to 30 feet in most areas. (Mapped as MDc in Flynn Creek structure, where it is about 200 feet thick.) (Also mapped as MDc on the East Sheet)

Gizzard Group, including Signal Point Shale, Warren Point Sandstone, and Raccoon Mountain Formation (Pennsylvanian) at surface, covers 0.3 % of this area

Gizzard Group - Shale, siltstone, sandstone, and conglomerate; from base of Sewannee Conglomerate to top of Mississippian. Thickness 0 to 520 feet, including Signal Point Shale - Mostly dark-gray to light-brown shale, with minor siltstone. Wilder coal near top. Thickness 0 to 180 feet, average about 60 feet; Warren Point Sandstone - Sandstone and conglomeratic sandstone, gray to brown, fine- to medium-grained, locally interbedded with shale containing coal. Thickness 0 to 300 feet, thins from southeast to northwest, average thickness about 100 feet; Raccoon Mountain Formation - Shale, siltstone, and sandstone. Bon Air coal near top; White Oak and Sale Creek coals near base. Thickness 0 to 260 feet.