Marl, a natural mixture of clay and calcium carbonate. It is a loose, earthy substance, usually gray or bluish in color. Marl deposits are formed in shallow lakes. The calcium carbonate marl is derived from the biological action of certain aquatic plants on dissolved carbonates. Shell marl contains shellfish remains. Greensand marl contains glauconite, or greensand, a silicate of potassium and iron. Marl is used to neutralize acid soils. Portland cement is sometimes made with marl instead of limestone.
Condensation, the formation of a liquid from a vapor or gas. It occurs in the formation of clouds and when cooled, water vapor turns into dew or rain.
Eros is 21 miles long and 8 miles thick -- a mini planet! Explore the mission that landed on this asteroid after orbiting it for a year!