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Silicon enters the ocean in a dissolved form such as silicic acid or silicate. [103] Since diatoms are one of the main users of these forms of silicon, they contribute greatly to the concentration of silicon throughout the ocean. Silicon forms a nutrient-like profile in the ocean due to the diatom productivity in shallow depths. [103]
The map of North America with the Western Interior Seaway during the Campanian. The Western Interior Seaway (also called the Cretaceous Seaway, the Niobraran Sea, the North American Inland Sea, or the Western Interior Sea) was a large inland sea that split the continent of North America into two landmasses for 34 million years.
In the deep ocean, another 26.2 Tmol Si Year −1 is dissolved before being deposited to the sediments as opal silica. [20] At the sediment water interface, over 90% of the silica is recycled and upwelled for use again in the photic zone. [20] Biogenic silica production in the photic zone is estimated to be 240 ± 40 Tmol si year −1. [36]
A replica of the Spanish carrack Santa Maria which was used by Christopher Columbus in his first expedition across the Atlantic Ocean in 1492, arriving to the New World A replica of the Portuguese carrack Flor de la Mar. participated in decisive events for Portugal in the Indian Ocean until her sinking in November 1511 The Mayflower II, a ...
Berzelius is credited with discovering the chemical elements cerium and selenium and with being the first to isolate silicon, thorium, titanium and zirconium. Berzelius discovered cerium in 1803 [29] and selenium in 1817. [30] Berzelius also discovered how to isolate silicon in 1824, [31] and thorium in 1824.
700 BC: Pell's equations are first studied by Baudhayana in India, the first diophantine equations known to be studied. [19] 700 BC: Grammar is first studied in India (note that Sanskrit Vyākaraṇa predates Pāṇini). [20] 600 BC: Thales of Miletus is credited with proving Thales's theorem. [21] [22] [23]
1620 Dutch inventor Cornelis Drebbel builds the world's first submarine and makes several trips in the River Thames near London at a depth of about 12 or 15 feet. 1698-1700 Edmund Halley made probably the first primarily scientific voyage to study the variation of the magnetic compass, sailing as far as 52 deg S. in the Atlantic Ocean.
Christopher Columbus [b] (/ k ə ˈ l ʌ m b ə s /; [2] 1451 – 20 May 1506) was an Italian [3] [c] explorer and navigator from the Republic of Genoa [3] [4] who completed four Spanish-based voyages across the Atlantic Ocean sponsored by the Catholic Monarchs, opening the way for the widespread European exploration and colonization of the Americas.