unconformity

Precambrian-Pennsylvanian nonconformity (Red Rocks Park, west of Denver, Colorado, USA) 29
by James St. John

Precambrian-Pennsylvanian nonconformity (Red Rocks Park, west of Denver, Colorado, USA) 19
by James St. John

Angular unconformity - Flagstaff Formation over Twist Gulch Formation (Salina Canyon, central Utah, USA) 69
by James St. John

White fossiliferous chert nodule in fossiliferous limestone (Columbus Limestone, Middle Devonian; Emerald Parkway roadcut, Dublin, Ohio, USA) 6
by James St. John

Pottsville Group over Maxville Limestone (East Fultonham Pit, Muskingum County, Ohio, USA) 8
by James St. John

Shinarump Conglomerate over De Chelly Sandstone (Upper Triassic over Lower Permian; Canyon de Chelly, Arizona, USA) 8
by James St. John

White fossiliferous chert in limestone (Columbus Limestone, Middle Devonian; Emerald Parkway roadcut, Dublin, Ohio, USA) 4
by James St. John

Pottsville Group over Maxville Limestone (East Fultonham Pit, Muskingum County, Ohio, USA) 10
by James St. John

Angular unconformity - Flagstaff Formation over Twist Gulch Formation (Salina Canyon, central Utah, USA) 40
by James St. John

Moellerina greenei (fossil charophyte oogonia) in fossiliferous limestone (Columbus Limestone, Middle Devonian; Emerald Parkway roadcut, Dublin, Ohio, USA) 5
by James St. John

Angular Unconformity 07-29
by paleololigo

Angular unconformity - Flagstaff Formation over Twist Gulch Formation (Salina Canyon, central Utah, USA) 60
by James St. John

Fossiliferous limestone (Columbus Limestone, Middle Devonian; Emerald Parkway roadcut, Dublin, Ohio, USA) 8
by James St. John

Columbus Limestone (Middle Devonian; Wright Run Creek, Dublin, Ohio, USA) 2
by James St. John

Olentangy Shale-Ohio Shale contact (Devonian; Lazarus Run, Delaware County, Ohio, USA) 2
by James St. John

Fossiliferous limestone (Columbus Limestone, Middle Devonian; Emerald Parkway roadcut, Dublin, Ohio, USA) 7
by James St. John

Halite salt casts in hematitic mudshale (Twist Gulch Formation, Middle Jurassic; float near small copper mine in Salina Canyon, Utah, USA) 9
by James St. John

Angular unconformity - Flagstaff Formation over Twist Gulch Formation (Salina Canyon, central Utah, USA) 10
by James St. John

Cross-bedded sandstone above an angular unconformity (Flagstaff Formation, Paleocene; Salina Canyon, central Utah, USA)
by James St. John

Angular unconformity - Flagstaff Formation over Twist Gulch Formation (Salina Canyon, central Utah, USA) 61
by James St. John

Precambrian-Cambrian disconformity (Three Sisters Range, South Australia) 7
by James St. John

Precambrian-Cambrian disconformity (Three Sisters Range, South Australia) 5B
by James St. John

Columbus Limestone (Middle Devonian; Emerald Parkway roadcut, Dublin, Ohio, USA) 18
by James St. John

Precambrian-Pennsylvanian nonconformity (Red Rocks Park, west of Denver, Colorado, USA) 28
by James St. John

Halite salt casts in hematitic mudshale (Twist Gulch Formation, Middle Jurassic; float near small copper mine in Salina Canyon, Utah, USA) 10
by James St. John

Pottsville Group over Maxville Limestone (East Fultonham Pit, Muskingum County, Ohio, USA) 7
by James St. John

Phosphatic nodule (Maury Shale, Lower Mississippian; Rt. 61 roadcut south of the Cumberland River, Cumberland County, Kentucky, USA) 3
by James St. John

Sandstone & basal lag above an angular unconformity (Flagstaff Formation, Paleocene; Salina Canyon, central Utah, USA)
by James St. John

Columbus Limestone-Delaware Limestone contact (Middle Devonian; Emerald Parkway roadcut, Dublin, Ohio, USA) 1
by James St. John

Angular unconformity - Flagstaff Formation over Twist Gulch Formation (Salina Canyon, central Utah, USA) 11
by James St. John

Partially silicified rugose coral in limestone (Columbus Limestone, Middle Devonian; Emerald Parkway roadcut, Dublin, Ohio, USA)
by James St. John

Shinarump Conglomerate over De Chelly Sandstone (Upper Triassic over Lower Permian; Canyon de Chelly, Arizona, USA) 17
by James St. John

Columbus Limestone-Delaware Limestone boundary bed (Middle Devonian; Emerald Parkway roadcut, Dublin, Ohio, USA) 2
by James St. John

Angular unconformity - Flagstaff Formation over Twist Gulch Formation (Salina Canyon, central Utah, USA) 67
by James St. John

Shinarump Conglomerate over De Chelly Sandstone (Upper Triassic over Lower Permian; Canyon de Chelly, Arizona, USA) 22
by James St. John

Fossiliferous limestone (Columbus Limestone, Middle Devonian; Emerald Parkway roadcut, Dublin, Ohio, USA) 9
by James St. John

Pikes Peak Granite (Mesoproterozoic, 1.08 Ga; Ute Trail, Manitou Springs, Colorado, USA) 6
by James St. John

Dolostone (Knox Dolomite, Upper Cambrian; Warren County core, Ohio, USA) 8
by James St. John

Quartz-pebble conglomerate (Sharon Conglomerate, Lower Pennsylvanian; Toboso East railroad cut, Licking County, Ohio, USA) 2
by James St. John

Columbus Limestone (Middle Devonian; Emerald Parkway roadcut, Dublin, Ohio, USA) 10
by James St. John

Halite salt casts in hematitic mudshale (Twist Gulch Formation, Middle Jurassic; float near small copper mine in Salina Canyon, Utah, USA) 12
by James St. John

Angular unconformity (basalt lava flow over redbeds; St. George, Utah, USA) 6
by James St. John

Fossiliferous limestone (Columbus Limestone, Middle Devonian; Emerald Parkway roadcut, Dublin, Ohio, USA) 6
by James St. John

Precambrian-Cambrian nonconformity (Sawatch Sandstone over Pikes Peak Granite; Ute Trail, Manitou Springs, Colorado, USA) 1
by James St. John

Angular unconformity - Flagstaff Formation over Twist Gulch Formation (Salina Canyon, central Utah, USA) 8
by James St. John

Precambrian-Cambrian nonconformity (Sawatch Sandstone over Pikes Peak Granite; Ute Trail, Manitou Springs, Colorado, USA) 4
by James St. John

Phosphatic nodule (Maury Shale, Lower Mississippian; Rt. 61 roadcut south of the Cumberland River, Cumberland County, Kentucky, USA) 4
by James St. John

Angular unconformity - Flagstaff Formation over Twist Gulch Formation (Salina Canyon, central Utah, USA) 12
by James St. John

Fossiliferous limestone (Columbus Limestone, Middle Devonian; Emerald Parkway roadcut, Dublin, Ohio, USA) 4
by James St. John

Precambrian-Cambrian disconformity (Three Sisters Range, South Australia) 3
by James St. John

Precambrian-Cambrian nonconformity (Sawatch Sandstone over Pikes Peak Granite; Ute Trail, Manitou Springs, Colorado, USA) 2
by James St. John

Columbus Limestone (Middle Devonian; Emerald Parkway roadcut, Dublin, Ohio, USA) 19
by James St. John

Shinarump Conglomerate over De Chelly Sandstone (Upper Triassic over Lower Permian; Canyon de Chelly, Arizona, USA) 5
by James St. John

Columbus Limestone-Delaware Limestone boundary bed (Middle Devonian; Emerald Parkway roadcut, Dublin, Ohio, USA) 3
by James St. John

Fossiliferous limestone (Columbus Limestone, Middle Devonian; Emerald Parkway roadcut, Dublin, Ohio, USA) 16
by James St. John

Angular unconformity - Flagstaff Formation over Twist Gulch Formation (Salina Canyon, central Utah, USA) 7
by James St. John

Angular unconformity - horizontal Tonto Group (Cambrian) over tilted Grand Canyon Supergroup (1.1-1.2 Ga), Grand Canyon, Arizona 4
by James St. John

Basal lag above an angular unconformity (Flagstaff Formation, Paleocene; Salina Canyon, central Utah, USA)
by James St. John

Pictured-Rx. 8
by James St. John

Angular unconformity - Flagstaff Formation over Twist Gulch Formation (Salina Canyon, central Utah, USA) 68
by James St. John