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.
Volcanic islands are formed by volcanic activity on the seabed, often near the boundaries of the tectonic plates that form Earthâs crust.Where two plates pull apart, lava erupts to form an undersea ridge. Layers of lava build up until a ridge breaks the seaâs surface to form an island.olcanic islands are formed by volcanic activity on the seabed, often near the boundaries of the tectonic plates that form Earthâs crust.