ch1 intro
Terms
undefined, object
copy deck
- Abyssal plain
- A flat area of the ocean floor separating the continental margins from the mid-ocean ridges .
- Asthenosphere
- A layer of soft but solid, mobile rock making up the lower part of the upper mantle from about 100 to 350 kilometers beneath the Earth's surface. The asthenosphere separates the lower mantle from the lithosphere. For plate tectonics to occur, the lithosphere must detatch from lower layers. This separation occurs in the relatively weak asthenosphere.
- Atmosphere
- The gaseous envelope held near the Earth by gravity. It consists by volume of about 3/4 nitrogen, and 1/5 oxygen, with smaller amounts of argon and carbon dioxide, together with minute quantities of helium, krypton, neon, and xenon.
- Biosphere
- All living organisms of the Earth and its atmosphere. This includes all the area occupied or favorable for occupation by living organisms in the lithosphere, hydrosphere, and atmosphere.
- Catastrophism
- The hypothesis that a series of immense, brief, worldwide upheavals changed the Earth's crust greatly and can account for the development of mountains, valleys, and other features of the Earth. In the mid-1600s, James Ussher promoted catastrophism by stating that the earth was just 4004 years old. This age was estimated from father-to-son listings in the Bible.
- Continental margin
- The zone of transition from a continent to the adjacent ocean basin. The continental margin is underwater.
- Core
- The innermost layer of the Earth, consisting primarily of pure metals such as iron and nickel. The core is the densest layer of the Earth. It is divided into the outer core, which is believed to be liquid, and the inner core, which is believed to be solid.
- Crust
- The outermost layer of the Earth, consisting of relatively low-density rocks. Continental crust is less dense than oceanic crust. Both crusts make up the upper part of the lithosphere.
- Deep-ocean basin
- A low part of the lithosphere lying between continental masses. The rocks of an ocean basin are mostly basalt with a thin top layer of oceanic sediment.
- Deep-ocean trench
- A deep, linear, relatively narrow depression in the sea floor, formed by the subduction of oceanic plates.
- Fossil succession
- When fossils are present in sedimentary rocks, the relative ages of the rocks can be determined from an examination of the fossils they contain. This is because fossils (found in layers) occur in a consistent vertical order in sedimentary rocks all over the world.
- Geology
- The scientific study of the Earth, its origins and evolution, the materials that make it up, and the processes that act on it.
- Historical geology
- Historical geology is the use of the principles of geology to reconstruct and understand the history of the Earth. It focuses on geologic events that change the Earth's surface and the use of stratigraphy to tell the sequence of these events. It also focuses on the evolution of plants and animals during different time periods in the Geologic timescale.
- Hydrosphere
- The part of the Earth composed of water including clouds, oceans, seas, ice caps, glaciers, lakes, rivers, underground water supplies, and atmospheric water vapor.
- Hypothesis
- A tentative explanation of a given set of data that is expected to remain valid after future observation and experimentation.
- Igneous rock
- A rock made from molten (melted) or partly molten material that has cooled and solidified.
- Inner core
- The central part of the Earth's core, extending from a depth of about 5,100 km to the center (6,371 km) of the Earth. Its radius is about one-third of the whole core. Earthquake studies suggest that the inner core is probably solid.
- Lithosphere
- A layer of solid, brittle rock making up the outer 100 kilometers of the Earth, encompassing both the crust and the outermost part of the upper mantle.
- Lower mantle (mesosphere)
- The deepest section of the mantle, stretching from 670 km down to the core-mantle boundary
- Mantle
- The middle layer of the Earth, separating the crust from the core. The mantle is made up of relatively dense rocks. It is divided into two sections, the upper mantle (less dense) and the lower mantle (more dense).
- Metamorphic rock
- A rock that has undergone chemical or structural changes. Heat, pressure, or a chemical reaction cause these changes.
- Nebular hypothesis
- The idea that our solar system formed from a gaseous cloud known as an "accretion disc". Early supporters of the idea argued that nebulae slowly rotate, gradually condensing and flattening due to gravity, eventually forming stars and planets.
- Negative feedback mechanism
- A process acting to balance or "dampen" the potentially disruptive effects of external input. It acts as a stabilizing mechanism.
- Oceanic ridge (mid-ocean
- A long, narrow chain of underwater mountains formed when two of the earth’s plates separate and magma swells up to the surface to form a new sea floor.
- Outer core
- The layer located directly under the mantle. The outer core is composed of liquid nickel and iron. Scientists believe that the outer core is liquid.
- Physical geology
- Physical geology includes mineralogy, the study of the chemical composition and structure of minerals; petrology, the study of the composition and origin of rocks; geomorphology, the study of the origin of landforms and their modification by dynamic processes; geochemistry, the study of the chemical composition of earth materials and the chemical changes that occur within the earth and on its surface; geophysics, the study of the behavior of rock materials in response to stresses and according to the principles of physics; sedimentology, the science of the erosion and deposition of rock particles by wind, water, or ice; structural geology, the study of the forces that deform the earth's rocks and the description and mapping of deformed rock bodies; economic geology, the study of the exploration and recovery of natural resources, such as ores and petroleum; and engineering geology, the study of the interactions of the earth's crust with human-made structures such as tunnels, mines, dams, bridges, and building foundations.
- Positive feedback mechanism
- A Feedback loop increasing the effect of an input to a system and leading to increased change.
- Rock cycle
- A series of events through which a rock changes (over time) from igneous, sedimentary, and metamorphic forms.
- Sedimentary rock
- A rock made from the consolidation of solid fragments (other rocks or organic remains) or by precipitation of minerals from solution.
- Shield (stable platform)
- Broad areas of exposed ancient crystalline rocks in the cores of the Earth's continents. These rocks, which are typically the oldest on the continents, are usually more than 2.5 billion years old.
- Solar nebula
- The swirling gas surrounding the early Sun during the epoch of solar system formation, also referred to as the primitive solar system.
- Superposition
- The order in which rocks are placed or accumulated in beds one above the other, the highest bed being the youngest.
- Theory
- Comprehensive explanation of a given set of data that has been repeatedly confirmed by observation and experimentation and has gained general acceptance within the scientific community but has not yet been decisively proven.
- uniformitarianism
- The hypothesis that current geologic processes, such as the slow erosion of a coast under the impact of waves or the development of oxbow lakes, have been occurring in a similar manner throughout the Earth's history and that these processes can account for past geologic events.
- oxbow lake
- A crescent-shaped body of standing water formed from a single loop that was cut off from a meandering stream, typically by a flood that allowed the stream to flow through its floodplain and bypass the loop.