After the Acadian collision took place , Gondwana began to retreat from Laurentia with the newly accreted Avalonian terranes left behind .
The collision creating the Acadian orogeny resulted in the closing of the southern Iapetus ocean and the formation of a high mountain belt .
After the Acadian orogeny collision took place , Gondwana began to retreat from Laurentia with the newly accreted Avalonian terranes left behind .
The collision creating the Acadian orogeny resulted in the closing of the southern Iapetus ocean and the formation of a high mountain belt .