Where did the basalt in the Columbia Gorge come from?
They originated from vents between Pendleton, Oregon and Hanford, Washington. The Frenchman Springs Member flowed along similar paths as the Grande Ronde basalts, but can be identified by different chemical characteristics.
What created the Columbia River basalts?
Flood basalt lava flow in stacked layers viewed eastward across the Columbia River from Rowena Crest Viewpoint, Oregon. Basalt in the lava flows has formed columnar jointing. The basalt columns formed when thick lava flows cooled after emplacement.
What were the main vents of the Columbia River basalts and where are they located?
The Columbia River Basalt is massive fissure lava flows which covered quite a bit of Idaho, Washington State, and Oregon. The majority of the CRBG flows are Early Miocene and are between 17 and 6 million years old. They were erupted from north-south fissures near the present-day Washington-Idaho border.
How thick is the Columbia River Basalt?
Under the Monument, these basaltic lava deposits (called the Columbia River Basalt Group) are over 13,000 feet thick. Although the Columbia River Basalt Group is one of the smallest flood-basalt areas, the individual lava flows that comprise the area are some of the largest found on Earth.
How hard is basalt rock?
On the Mohs scale of mineral hardness, basalt scores a six – meaning it’s harder than platinum or iron.
Does the Columbia River flood?
The Columbia River has a long history of flooding. Flood stage for the river, as measured near the Port of Vancouver, is 16 feet. The following are the 25 historic crests of the Columbia River, as well as what you can expect when the river reaches certain heights.
How old is the Columbia River flood basalt?
The Columbia River Basalt Group (CRBG) is the youngest, smallest, and best-preserved continental flood basalt. It erupted ~210,000 km3 of lava in the Pacific Northwest, United States, between ~17 and 5 million years (Ma) ago.
What are the 5 main composite volcanoes that pose hazards to those living in Washington?
Washington has five volcanoes that are listed as high or very high threat potential: Mount Baker, Glacier Peak, Mount Rainier, Mount St. Helens, and Mount Adams. These volcanoes are part of the Cascade Range, a 1,200-mile line of volcanoes from British Columbia to northern California.
Is basalt better than granite?
Basalt weathers faster than granite because it is not as hard and it’s easier for outside substances to impact and manipulate its structure.
What year did the Columbia River flood?
1894
June 7, 1894 – The Great Flood of 1894 The Columbia River reached an elevation of 39.7 feet, which is still the highest flood on record to this day.
When was the last flood in Vancouver Washington?
February 1996
Flooding near Vancouver Lake in February 1996. Clark County’s last big flood occurred in February 1996. Extended rainfall and early snowmelt, triggered by an influx of warm, wet weather known as the “Pineapple Express,” caused many rivers and creeks to flood.
How old is the Columbia River basalt group?
Formally called the Columbia River Basalt Group (CRBG), the flows are divided into five formations – the Saddle Mountains, Wanapum, Grande Ronde, Imnaha, and Picture Gorge Basalts. The majority of the CRBG flows are Early Miocene and are between 17 and 5.5 million years old.
Where are the basalt flows in the Columbia River Gorge?
Less extensive eruptions continued 14–6 million years ago. Erosion resulting from the Missoula Floods has extensively exposed these lava flows, laying bare many layers of the basalt flows at Wallula Gap, the lower Palouse River, the Columbia River Gorge and throughout the Channeled Scablands .
What kind of lava flows are the CRBG?
Basalt in the lava flows has formed columnar jointing. (Credit: Westby, Liz. Public domain.) The thick, layered lava flows of the CRBG erupted as flood basalts, which originate as some of the most highly effusive eruptions in the world.
What kind of lava flows are in the Columbia River?
The Columbia River Basalt is massive fissure lava flows which covered quite a bit of Idaho, Washington State, and Oregon. Formally called the Columbia River Basalt Group (CRBG), the flows are divided into five formations – the Saddle Mountains, Wanapum, Grande Ronde, Imnaha, and Picture Gorge Basalts.