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The gaseous envelope of a celestial body (as a planet)
5.
A remnant, impression, or trace of an organism of a past geologic age that has been preserved in the earth's crust.
6.
A community of organisms and their environment, functioning as an ecological unit.
8.
A device with fixed and moving parts that modifies mechanical energy in order to do work.
9.
The capacity for doing work.
10.
The gradual wearing away of rock or soil by physical breakdown, chemical solution, and/or transportation of material, as caused, for example, by water, wind, or ice.
Down:
1.
A modification of an organism or its parts that makes the organism more fit for existence under the conditions of its environment.
2.
A path described by one body in its revolution about another (e.g., Earth about the sun, an electron about an atomic nucleus.)
3.
The return of light or sound waves from a surface.
4.
The average course or condition of the weather at a place, usually over a period of years, as exhibited by temperature, wind velocity, and precipitation.
7.
The state of the atmosphere with respect to heat or cold, wetness or dryness, calm or storm, clearness or cloudiness.