Grand Canyon Supergroup Bass and Hakatai Transition 0017 - Flickr - Grand Canyon NPS
NPS Photo by: Carl Bowman Bass Limestone Thickness: 260-300 feet
A number of different sedimentary rock types (such as conglomerate, dolomite and shale) occur within this light grey to brown formation. The Bass Limestone contains fossilized stromatolites, which are among the oldest fossils in the world. Their presence allows scientists to infer that the Bass Limestone was deposited in a warm and shallow sea environment.
Hakatai Shale Thickness: 445-985 feet
This colorful formation contains layers of red sandstones, red shales, and blue to purple shales. As the sea level dropped, the environment slowly changed from a shallow sea to coastal mud flats. Mudcracks, raindrop impressions, and cross-beds are found in this layer.
Relevante Bilder
Relevante Artikel
Bass-FormationDie Bass-Formation ist ein geologischer Schichtenverband im Grand Canyon. Sie bildet das Liegende der zur Grand Canyon Supergroup gehörenden Unkar Group und ist während des Mesoproterozoikums im Rodinium/Ectasium vor rund 1250 Millionen Jahren abgelagert worden. .. weiterlesen