[pct-l] Oregon Sec B update

[Eric Lee]

Tortoise wrote:
>
If I recall correctly from my visit to Craters of the Moon National 
Monument last summer, when the  basalt is first broken it is the rusty 
red color you see and then it eventually changes to the dark brown one 
usually sees.
>


Hmmm.  I don't think that's right, actually.  Most basalt starts out
dark-colored but may, depending on its iron content, weather to a red color.
Cinders, with their high surface area, tend to weather faster and more
thoroughly.  That area does have a lot of red cinders that are used for
highway construction and the like.  Sometimes you can even see red paved
roads.

See this link, for example:
http://skywalker.cochise.edu/wellerr/rocks/igrx/basaltQ.htm

Disclaimer: I'm not a geologist.  :-)

The trail through the lava fields was covered with red cinders probably
because they're easy to dig out and relatively light to transport.

Eric