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 where they do because of the position of the crust over a plate boundary or a 'hot spot' in the Earth's mantle.olcanoes usually occur where there are collision of the tectonic plates. There are 52 tectonic plates which either pull (gap and crack) or push (volcano). Volcanoes are actually tectonic plates which have magmas beneath their outer surface.