Main Page

From Wikipedia, the free encyclopedia.

Jump to: navigation, search

Welcome to Wikipedia, the free encyclopedia that anyone can edit.

In this English version, started in 2001, we are currently working on 802,285 articles.

Today's featured article

The Grand Canyon, from Navajo Point

The geology of the Grand Canyon area exposes one of the most complete sequences of rock anywhere, representing a period of 1.4 billion years of the Earth's history in that part of North America. The major sedimentary rock layers exposed in the Grand Canyon and in the Grand Canyon National Park area range in age from 2 billion to about 200 million years old. Most were deposited in warm, shallow seas and near ancient, long-gone sea shores. Both marine and terrestrial sediments are represented, including fossilized sand dunes from an extinct desert. Uplift of the region started about 75 million years ago in the Laramide orogeny, a mountain-building event that is largely responsible for creating the Rocky Mountains to the east. The canyon did not start to form until 5.3 million years ago when the Gulf of California opened up and thus lowered the river's base level (its lowest point) from that of large inland lakes to sea level. About 2 million years ago volcanic activity started to deposit ash and lava over the area. The nearly 40 identified rock layers and 14 major unconformities (gaps in the geologic record) of the Grand Canyon form one of the most studied sequences of rock in the world.

Recently featured: Eigenvalue, eigenvector and eigenspaceGray WolfSpeaker of the House of Commons

Selected anniversaries

November 2: All Souls Day in Catholicism; Day of the Dead in Mexico.

Arthur Balfour

Recent days: November 1October 31October 30

In the news

David Blunkett
© Crown copyright

Did you know...

From Wikipedia's newest articles:

William Waldegrave, 1st Baron Radstock

Wikipedia in other languages

You may read and edit articles in many different languages:

Wikipedia encyclopedia languages with over 100,000 articles
Deutsch (German) · Français (French) · Italiano (Italian) · 日本語 (Japanese) · Nederlands (Dutch) · Polski (Polish) · Svenska (Swedish)

Complete list · Multilingual coordination · Start a Wikipedia in another language

Wikipedia's sister projects

Wikipedia is hosted by the non-profit Wikimedia Foundation, which operates several other multilingual and free-content projects:

Dictionary and thesaurus
Free textbooks and manuals
Collection of quotations
The free library
Directory of species
Free content news source
Shared media repository
Wikimedia project coordination

All New articles: 5 10 15 20 25 30 | Orphans: 5 | Categories: 45 50 55 60 65 70 75

Personal tools