. Fig. 1 shows North America during the Devonian period, about 375 million years

Question

. Fig. 1 shows North America during the Devonian period, about 375 million years ago. The long, narrow continent off the east coast is called Avalonia. The arrow indicates that it is moving towards the continent of Laurentia, what is now North America.

                A) What kind of plate margin must exist along the east coast of Laurentia in this diagram? What is happening to the oceanic plate between Laurentia and Avalonia?

B) What is the environment at this time in the place where Georgia is now? What kind of rocks form in that environment?

               

C) What would happen to the east coast of Laurentia once Avalonia collides with it?

Figure 1. Map of North America during the Devonian, showing the accretion of Avalonia onto Laurentia

Explanation / Answer

A) Since the continents are relatively coming closer, the margin that exists along the east coast of Laurentia should be Convergent Plate Margin.

According to Wilson Cycle, the oceanic plate is subducting beneath the continental plates of Laurentia and Avalonia.

B) Currently the Georgia is mainly under two type of environmental influences, 1) along the east, it has a marine influence which means rocks that will form will be basically sedimentary origin. 2). Along the west it has montainuous influence that means a region of folding and faulting often resulting in the metamorphism of presxisting rocks.

C) Once the Avalonia collides with the east coast of Laurentia, it will become a site of mountain building/orogeny. The Acadian highlands along the east coast of North America are beleived to have formed due to this mountain building activity.

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