Steps. 1  1. Perform major pruning during the dormant season. The ideal time to prune a crabapple tree is late winter or in the cold days of early spring, before leaves appear. 2  2. Remove suckers. Suckers are additional branches that begin growing underground and sprout near the base of the tree. 3  3. Remove water sprouts.
The upper crust is 12.5 km thick in crust with an average total thickness of 40 km (ref. 3). If the upper crust is the product of 14% melting, the corresponding residue would be 77 km thick, resulting in a total crustal thickness of 100 km, including the middle crust.
Continental Crust A layer of the earth's crust that lies under the seven continents. It is about 20 to 40 miles (35 to 70 km) thick and very old. Convergent Boundary The boundary that occurs where two plates are pushing toward each other. Crust Hard and rigid, the earth's outermost and thinnest layer. It is only a few miles (5 km) thick under the oceans and averages 20 miles (30 km) thick under the continents.