title: Mineral Fork Formation
text: # Mineral Fork Formation
  
  The Mineral Fork Formation is a mapped Proterozoic bedrock unit in Utah.
  
  ## Description
  
  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.
  
  ### Exposures
  
  According to Yonkee et al. (2000), the Mineral Fork is exposed at the following locations in Utah:
  
  * 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.
  
  