The Laramide Rockies formed between about 85-50 million years ago. A popular theory is this event was caused by "flat slab subduction" of over-thickened oceanic crust. From your understanding of mountain building processes in this part of the course, evaluate the following question(s). a. Was this mountain building process an Andean type mountain building event, a collisional event, or both; and what might have been subducted to produce the over-thickened oceanic crust that drove the orogeny? b. If these mountains formed 50 million years ago, why are they still high?