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.
A volcanic arc is a chain of volcanoes formed above a subducting plate, positioned in an arc shape as seen from above.Offshore volcanoes form islands, resulting in a volcanic island arc.Generally they result from the subduction of an oceanic tectonic plate under another tectonic plate, and often parallel an oceanic trench.The oceanic plate is saturated with water, and volatiles such as water drastically lower the melting point of the mantle.ffshore volcanoes form islands, resulting in a volcanic island arc. Generally they result from the subduction of an oceanic tectonic plate under another tectonic plate, and often parallel an oceanic trench.