- Antarctica - The World Factbook (cia.gov)
Speculation over the existence of a “southern land” was confirmed in the early 1820s when British and American commercial operators and British and Russian national expeditions began exploring the Antarctic Peninsula region and other areas south of the Antarctic Circle. In 1840, it was finally established that Antarctica was indeed a continent and not merely a group of islands or an area of ocean.
- Oxygen (Wikipedia)
Oxygen is a chemical element; it has symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. Oxygen is Earth’s most abundant element, and after hydrogen and helium, it is the third-most abundant element in the universe. At standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula O2. Diatomic oxygen gas currently constitutes 20.95% of the Earth’s atmosphere, though this has changed considerably over long periods of time. Oxygen makes up almost half of the Earth’s crust in the form of oxides.