What do cyclothems represent? What will be an ideal ...

[Mr.Thesaxman]

What do cyclothems represent? What will be an ideal response?

Question 2

Describe what happened to create the Sauk sequence from its beginning to the beginning of the
  Tippecanoe sequence. What will be an ideal response?

[spencer.martell]

Answer to Question 1

Cyclothems result from repeated alternations of marine and nonmarine environments, usually in areas
of low relief. Cyclothems represent transgressive and regressive sequences with an erosional surface
separating one cyclothem from another. An idealized cyclothem passes upward from fluvial-deltaic
deposits, through coals, to detrital shallow-water marine sediments, and finally to limestones typical of
an open marine environment.

Answer to Question 2

During the Middle Cambrian, shallow seas encroached over the craton, beginning the transgressive
phase of the Sauk. By Late Cambrian, the sea covered most of North America with the exception of a
portion of the Canadian shield and a few large islands named the Transcontinental Arch. The Sauk Sea
regressed from the craton during the Early Ordovician, and the exposed rocks were eroded. A cratonwide
unconformity marks the boundary between the Sauk and Tippecanoe sequences.

[Mr.Thesaxman]

Excellent

[shailee]

Gracias!