 | Geological Society of America - 1899 - 706 стор.
...limestone, in thick layers, which weathers to a buff and in many places to a light gray color. 1 rregular bands of broken oolitic and concretionary limestone...occur at various horizons. Bands of dark and gray silicious shale and greenish and pur!'h>h argillaceous shale are interbedded in the limestones. These... | |
 | Thomas Chrowder Chamberlin - 1906 - 1060 стор.
...bluish-gray and gray limestone, in thick layers, which weathers to a buff and in many places to a light gray color. Irregular bands of broken oolitic and concretionary...occur at various horizons. Bands of dark and gray silicious shale and greenish and purplish argillaceous shale are interbedded in the limestones. These... | |
 | Thomas Chrowder Chamberlin - 1906 - 850 стор.
...bluish-gray and gray limestone, in thick layers, which weathers to a buff and in many places to a light gray color. Irregular bands of broken oolitic and concretionary...occur at various horizons. Bands of dark and gray silicious shale and greenish and purplish argillaceous shale are interbedded in the limestones. These... | |
 | Joseph Barrell - 1919 - 620 стор.
...bluish-gray and gray limestone, in thick layers, which weathers to a buff and in many places to a light gray color. Irregular bands of broken oolitic and concretionary...occur at various horizons. Bands of dark and gray silicious shale and greenish and purplish argillaceous shale are interbedded in the limestones. These... | |
 | Joseph Barrell - 1907 - 242 стор.
...more or less impure bluish-gray and gray limestone, in thick layers, which weathers to a buff or pink and in many places to a light-gray color. Irregular...inch to several feet in thickness. There are also layers of thinner bedded limestones, especially toward the top of the formation. The formation is so... | |
 | Geological Society of America - 1899 - 668 стор.
...gray and gray limestone, in thick layers, which weathers to a buff and in many places to a light gray color. Irregular bands of broken oolitic and concretionary...limestone occur at various horizons. Bands of dark and gra3- silidous shale and greenish and purplish argillaceous shale are interbedded in the limestones.... | |
| |
The Helena limestone formation is composed of more or less impure bluish-gray and gray limestone, in thick layers, which weathers to a buff and in many places to a light gray color. Irregular bands of broken oolitic and concretionary limestone occur at... 