- Lead is a chemical element; it has symbol Pb (from Latin plumbum) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cut, lead is a shiny gray with a hint of blue. It tarnishes to a dull gray color when exposed to air. Lead has the highest atomic number of any stable element and three of its isotopes are endpoints of major nuclear decay chains of heavier elements.
- Columbia River drainage basin (Wikipedia)
The Columbia River drainage basin is the drainage basin of the Columbia River in the Pacific Northwest region of North America. It covers 668,000 km2 or 258,000 sq mi. In common usage, the term often refers to a smaller area, generally the portion of the drainage basin that lies within eastern Washington.