Rarely a serious problem. Look-alikes: Jumping oak gall, tubakia leaf spot, oak leaf blister, other fungal leaf spots. Jumping oak gall Brown leaves appear on trees in the white oak group in late spring. Severe infections may cause the leaves to turn black, curl up and fall. On the underside are brown galls with the larva of a small wasp inside.
Volcanoes form when magma reaches the Earth's surface, causing eruptions of lava and ash. They occur at destructive (compressional) and constructive (tensional) plate boundaries. The immediate effects of volcanic eruptions can be devastating, but they may be beneficial in the long term.
Volcanoes occur at divergent plate boundaries because of the new crust formed by solidifying of magma on the ocean bed which is very weak so the heat and pressure from the magma chamber will become too high to handle and there will be an eruption. Volcanoes form where the earth's crust is thin an the magma can flow to the surface easier.