DESCRIPTIONS: Formational contacts represent shifts in ancient environments that are displayed in rapid changes in rock color, composition, texture of sediments and bedding thicknesses.
Figure 1 - Contact between Ankareh (Triassic), red and maroon shales and purple limestone and the overlying Nugget (Jurassic), buff to pink Quartz Sandstone. Sage Junction, WY. (Photo 1983)
Figure 2 - Contact between Woodside Fm. (red) (Triassic) and Thaynes (Fm) (Triassic) at Wolfe Mountain, WY exposed on a steep cliff. (Photo 1983)
Figure 3 - Contact between Woodside Fm. (red) (Triassic) and Thaynes (Fm) (gray) (Triassic) at Wolf Mountain, WY. Beds are inclined. Woodside sediments are composed largely of shale which weathers easily into a reddish soil which supports pant life. (Photo 1983)
Figure 4 - Some contacts are subtle as is seen here between the Ordovician Carters Fm. below the hammer (relatively thick limestone beds) and the Hermitage Fm above the hammer (argillaceous thin-bedded limestone).
Figure 5- Subtle contact between the Ordovician Hermitage argillaceous limestone below the hammer and the thicker bedded limestone beds of the Cannon Fm. above the hammer.