Mineral Fork Formation

Granger et al. (1952) describe the Mineral Fork Formation as black tillite consisting of boulders, cobbles and pebbles of quartzite, limestone, or granitic rocks in a black sandy matrix, with dark-gray to black varved slate or shale, dark-gray quartzite, and occasional channel fillings of boulder conglomerate. • Antelope Island • Big Cottonwood Canyon • Santaquin-Provo And also: • Little Cottonwood Canyon Fossils Abundant microfossils of planktonic alga of Bavlinella faveolata. ==Age==

The presence of Bavlinella faveolata in the formation indicates a likely age of 750–650 Ma, because this fossil occurs elsewhere where it is well-dated radiometrically. The Mineral Fork Formation is no older than 1,250 Ma and no younger than 540 Ma. Thus it is likely Neoproterozoic but possibly Mesoproterozoic. ==References==