as mentioned previously, the acadian orogeny formed from the oblique convergence or major transcurrent movement along a large strike-slip fault moving in a southeasterly direction. avalonian terranes accreted to the eastern margin of laurentia during the late to middle devonian. this was a continent-continent collision with baltica/avalonia obliquely subducting below the eastern laurentia margin, which closed the southern iapetus ocean and created a high mountain belt.