1539 | First exploration of the Southwest by Coronado. |
1851 | Petrified wood first reported in northern Arizona by Lieutenant
Sitgreaves. |
1853 | Petrified Forest Monument area visited by Army expedition
headed by Lieutenant Whipple. |
1857 | Camel caravan of Lieutenant Beale crossed area. |
1898 to 1900 | First Government investigation of the area made by Lester F.
Ward of the U. S. Geological Survey. |
1906 | Petrified Forest set aside as a national monument by President
Theodore Roosevelt. |
1906 | John Muir discovered, explored, and named the Blue Forest. |
1911 | Agate Bridge supported by stone pillars, replaced by present
reinforced concrete beam in 1917. |
1921 to 1929 | Phytosaurs excavated in Blue Forest. |
1930 | Blue Forest and Newspaper Rock included in the monument by President Hoover. |
1932 | Painted Desert area added to the monument by President Hoover. |
1932 | Completion and dedication of Puerco River Bridge, making area accessible
to motorists. |
1933 | Agate House restored and three rooms of Puerco River Ruin excavated. |
1933 to 1940 | Fossil leaf beds of Blue Forest discovered, explored, and described. |
1940 | Painted Desert Inn and Museum completed. |