| What: A dark igneous rock known as Basalt covers southeastern
Washington. Any Lava with less than 53% silicon is known as Basalt and the
lesser amount of silicon allows this lava to flow miles from its source
creating a variety of scenery unparalleled in the world. Different cooling
rates due to weather, proximity of water, and the volume of the flow cause
a seemingly uncountable variety of type of structure. The slideshow above
attempts to show some of this variety. The rock is frequently weathered
reddish brown, varnished by bacteria to a dark black, or covered with
algaes to hues of green, yellow, and red. This massive substance
that can easily be seen on nearly all east-west highways with its massive
layers, fluted columns, and fractured faces, welled up from subterranean
chambers to spread over vast areas in the northwest basin.
As I find what I feel are significantly
differing examples of basalt formation I will post their pictures and
any descriptions here.
When you look at these formations, it might help to think of water
erosion tearing at smooth rock walls with varying densities. The weak
stuff crumbles, the strong dense stuff remains.
Another interesting thing that basalt lava flows do is if something is
covered with water before the lava covers it, the item is not always
burned up by the lave flow because the water and the temperature of the
item cools the lava around the item and a cast of the item is then made
that makes a three dimensional picture of the item which can be studied
millions of years later if the item is eroded. The item that has erosion
take place to expose it is then rotted out and the cavity or cast is left
of the item. I have photographic evidence of 2 instances of this happening
in this area: Devil's Well and
Blue Lake Rhino.
One form of basalt not pictured above is the ash form like that which
fell on Spokane in 1980 from Mt St. Helens.
In New Zealand there is a unique formation of basalt.
Click here to see pictures
and read about it. |
