back acid, (adjective—acidic) — having a pH of less than 7 alkaline — having a pH of MORE than 7 basalt — a volcanic rock. Basalt is the most common type of rock found in the Earth's crust. buckskin — strong, soft leather Bunsen burner — a small burner used in a laboratory. It usually consists of a metal tube connected to a gas source and produces heat from a mixture of gas and air let in from holes at its base. caldera — a large crater formed from a collapsed volcano chemical compound — a substance composed of two or more different elements in definite proportions and usually having properties different from those of its elements circulation — flow or movement through a system constriction — a narrowing or tight place diameter — the width of an object earthquake — a series of waves in the crust of the Earth, resulting in movements on the Earth’s surface element — a substance whose atoms have a identical number of protons in each nucleus erupt — to explode or release lava and gases during volcanic activity exchange of function — the shifting of heat and water flow between hydrothermal features geyser — a hot spring that erupts at periodic intervals and throws water forcibly into the air groundwater — water beneath the Earth’s surface hotspot — an area on the Earth’s surface that shows signs of long-lasting volcanic activity hydrogen sulfide — a poisonous gas composed of hydrogen and sulfur and having a rotten egg smell hydrothermal — having to do with hot water interval — the length of time between occurrences lava — molten rock mineral — a solid that occurs naturally and has a definite chemical composition. A mineral’s atoms usually form a regular pattern. pH — the level of acidity in water, ranging from 0-14 precipitation — rain, snow, sleet, etc. quartz — a hard crystalline mineral found throughout the world, also known as silicon dioxide rhyolite, (adjective—rhyolitic) — a volcanic rock similar in composition to granite Sherlock Holmes — a fictional English detective silica — the crystalline compound of silicon and oxygen silicon — an basic element of the Earth’s crust treacherous — dangerous vandalize — to purposely destroy or damage volcano — a vent in the Earth’s crust through which lava, ashes, and hot gases are released back This material is based on work supported by the National Science Foundation under Grant No.0307709 Funding for this trip was provided by generous grants to the Yellowstone Park Foundation. Home | For Teachers | Ask An Expert | Evaluation | Contact Us ©The Yellowstone Park Foundation 2004 Privacy Disclaimer | Freedom of Information Act