- The Silurian (/sɪˈljʊəriːən, saɪ-/ sih-LURE-ee-ən, sy-) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at 443.8 million years ago (Mya), to the beginning of the Devonian Period, 419.2 Mya. The Silurian is the shortest period of the Paleozoic Era. As with other geologic periods, the rock beds that define the period’s start and end are well identified, but the exact dates are uncertain by a few million years. The base of the Silurian is set at a series of major Ordovician–Silurian extinction events when up to 60% of marine genera were wiped out.
- United States Declaration of Independence (Wikipedia)
The Declaration of Independence, formally titled The unanimous Declaration of the thirteen united States of America (in the engrossed version but not the original printing), is the founding document of the United States. On July 4, 1776, it was adopted unanimously by the 56 delegates to the Second Continental Congress, who had convened at the Pennsylvania State House, later renamed Independence Hall, in the colonial era capital of Philadelphia. The declaration explains to the world why the Thirteen Colonies regarded themselves as independent sovereign states no longer subject to British colonial rule.