The Wilson Cycle (a.k.a. Supercontinent
Cycle) (p. 407-409) – you should know this!
Embryonic Stage – e.g. East African Rift
Immature Stage - e.g. Red Sea
Mature Stage - e.g. Atlantic Ocean
Declining Stage - e.g. Pacific Ocean
Remnant Stage - e.g. Mediterranean Ocean
Suture Stage - e.g. Himalayas
The Opening of an Ocean Basin: (see fig. 13.19)
Embryonic Stage: volcanic and non-marine sediment deposited in
rift valleys – e.g. the East African Rift (fig. 13.18)
Immature Stage: continued rifting creates new oceanic crust and
a long, linear marine seaway. Cooling and subsidence of the rifted margin allow
sediment to be deposited – e.g. the Red Sea (fig. 13.18)
Mature Stage: A broad ocean develops and the continental margin continues to
grow as sediment derived from erosion of the land is deposited. Typically
rimmed with passive continental margins – e.g. the Atlantic Ocean (fig. 13.12)
The Closing of an Ocean Basin:
Declining Stage: an ocean basin that has begun to get smaller.
New oceanic lithosphere is forming at a rate less than the rate at which it is
being consumed at convergent margins. Typically rimmed with active continental
margins– e.g. the Pacific Ocean
Remnant Stage: A small remnant of an ocean which has largely consumed - e.g.
the Mediterranean Ocean (fig. 14.9A)
Suture Zone: The sutured margin where an ocean basin has been
completely consumed along a continent-continent convergent plate boundary – e.g.
the Himalayas (fig. 2.23; 14.9B; 14.11)
Some Study Questions:
Q. What type of faulting would you expect to
occur in the Rift Valleys?
Q. The Red Sea started out like the
rift valleys, but now is a (an) "__________ ocean"
Q. The Atlantic Ocean started out like
the Red Sea, but now is a (an) “__________ ocean”.
Q. Where are most Divergent Plate
Boundaries located? (fig. 13.12)
Q. How and why does the profile across the
Mid Atlantic Ridge differ from that across the East Pacific Rise?
Q. What are the differences between “passive”(fig.
13.7) and “active”(fig. 13.8) continental margins?
Q. Where does each occur today?
Q. The Pacific Ocean is getting smaller
everyday. How is that possible?
Q. Volcanic Island Arcs form under what tectonic
setting? (fig.14.4A)
Q. Where would you likely find a “passive”
continental margin? (fig. 14.7B)
Q. How did the Himalayas form? (fig. 2.23;
14.11)
Q. How (and when) did the Southern
Appalachian Mountains form? (fig. 14.12)
Q. What is the Valley and Ridge Province and
how does it differ from the Basin and Range Province? (fig. 14.13; fig. 14.18)
Q. How did the Cascade Mountains form? (fig. 2.25;
5.36)