Volcanoes are among the most spectacular features of the earth sciences, with explosive eruptions that create havoc and destruction in large areas, impact the local atmosphere with noxious gases, and ultimately may influence climate. What types of volcanoes exist on Earth, and how are they related to the larger framework of plate tectonics (the Ring of Fire, ocean islands like Hawaii)? What drives volcanic eruptions, what physical properties of magmas should we understand to predict eruptions and their impacts? This introductory course will treat the occurrence and distribution of volcanoes on Earth and discuss some of the major historic eruptions and their human impacts. We will look at the relation between volcanoes and ore bodies, geothermal energy, and climate change. We will make a short field trip to volcanic rocks in Connecticut, and we may try some experiments with our own "backyard" volcano.