A six-inch Torrey pine seedling can have a taproot two or three feet long. This will grow down rapidly, then branch out when it reaches bedrock. The roots will go anywhere they can find a little water and a little nutrient. By the time a tree is 40 feet high it may have roots reaching out 200 feet. We usually think of tree roots as preventing erosion.
Sometime roots can cause erosion.
A tree can give the appearance of growing out of solid rock. Its roots have followed a crack. If the fissure is near a cliff, the growing, swelling root system flakes off the edge and causes a minor landslide. You can see these mats of roots in many places along the cliffs. A slide can cause an occasional upside-down Torrey pine.