Confidence votes 278. America, referring to the United States, was officially 237 years old on July 4, 2013. If one dates from the adoption of the Constitution in 1787, the nation was 226 years old. The first explorations of the US mainland area by Europeans were by Spaniards in the early 16th Century.
Litharge is one of the natural mineral forms of lead oxide, PbO. Litharge is a secondary mineral which forms from the oxidation of galena ores. It forms as coatings and encrustations with internal tetragonal crystal structure. It is dimorphous with the orthorhombic form massicot. It forms soft, red, greasy-appearing crusts with a very high specific gravity of 9.14â9.35.
Groundwater recharge or deep drainage or deep percolation is a hydrologic process where water moves downward from surface water to groundwater. Recharge is the primary method that water enters an aquifer. This process usually occurs in the vadose zone below plant roots and is often expressed as a flux to the water table surface.