Chlorofluorocarbons (CFCs): Synthetic organic compounds first created in the 1950s and used primarily as refrigerants and as propellants. The role of CFCs in the destruction of the ozone layer led to the signing of an international agreement (the Montreal Protocol).
Anthropocene: Geological epoch defined by atmospheric chemist Paul Crutzen to acknowledge the central role humans play in shaping the Earth's environment.
Pangaea: The primeval supercontinent, hypothesized by Alfred Wegner, that broke apart and formed the continents and oceans as we know them today; consisted of two parts- a northern Laurasia and a southern Gondwana.
Tectonic Plates: Large pieces of rock that form portions of the Earth's mantle and crust and which are in motion.
Photosynthesis: The formation of carbohydrates in living plants from water and carbon dioxide, through the action of sunlight on chlorophyll in those plants, including algae.
Mass Depletions: Loss of diversity through a failure to produce new species.
Mass Extictions: Mass destruction of most species.
Pacific Ring of Fire: Ocean-girdling zone of crustal instability, volcanism, and earthquakes resulting from the tectonic activity along plate boundaries in the region.
Pleistocene: The most recent epoch of the late Cenozoic ice age, beginning about 1.8 million years ago and marked by as many as 20 glaciations and interglaciations of which the current warm phase, the Holocene epoch, has witnessed the rise of human civilization.
Glaciation: A period of global cooling during which continental ice sheets and mountain glaciers expand.
Interglacials: Warm periods during an ice age.
Wisconsin Glaciation: The most recent glacial period of Pleistocene, enduring about 180,000 years ago, to the current interglacial, the Holocene.
Holocene: The current interglaciation period, extending from 10,000 years ago to the present on the geologic time scale.
Little Ice Age: Temporary but