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.
Most volcanoes are formed by the movement of tectonic plates on the surface of the earth. These plates are basically huge pieces of rock that float on the mantle (a layer of the earth that is sort-of liquid rock).ost volcanoes are formed by the movement of tectonic plates on the surface of the earth. These plates are basically huge pieces of rock that float on the mantle (a layer of the earth that is sort-of liquid rock).