Question
My Mountain Maple has vertical splits in the trunk and a couple of the branches.  It looks like the tree is growing to fast and is splitting or cracking as the result. Other than this it appears to be healthy with a lot of leafs and seed pods.  I live in Denver where the weather has severe temperature extremes with hot temps this summer.

Answer
Maple has the tenancy for the bark to split due to the thin bark and fast growing nature. It is sometimes called sunscald and it is due to the changes in temperature. Thin barked trees often develop what we call 'sunscald', a type of winter injury. On sunny winter days, the cambium (thin layer of living tissue just beneath the bark) on the south or southwest side of these trees warms up nicely, much warmer than the air temperature, and this layer expands. When the sun goes down, the temperature of the woody tissue suddenly plummets, and because the outermost tissue cools faster than the inner tissue, a crack happens.

If the  foliage is green and healthy looking there is not a problem with the tree. To help protect the bark from mechanical damage make sure there is mulch around the tree base. Watch these bark areas and if you see signs of insect activity (sawdust or holes) spray the area with an insecticide for borers--check with your local nursery/garden type store for an insecticide for borers. Merit is one of the insecticides for borer control. If you wanted to you could go ahead and spray the bark about every three months--this would prevent borer attack.