quote:
From: Wood and Kienle, (eds.), 1990, Volcanoes of North America - United States and Canada: Cambridge University Press. Contribution by Donald A. Swanson
The Goat Rocks volcano is a deeply eroded, glaciated volcanic center in an area of wide-spread Pliocene and Pleistocene volcanism along the Cascade crest in southern Washington. Volcanism began approximately 3.2 million years ago with eruption of at least 650 meters of high-silica rhyolite tuff (perhaps a caldera fill), which is exposed on the east flank of the subsequent Goat Rocks volcano. The silicic volcanism ended approximately 3 million years ago, and olivine basalt was locally erupted onto the rhyolitic rocks. Soon thereafter lava flows of high-K2O andesite, dominantly pyroxene phyric but including flows with significant hornblende, formed the Goat Rocks volcano. The volcano was probably build between approximately 2.5 and 0.5 million years ago. Some large volume lava flows moved many kilometers downvalley away from the volcano. The most notable such flow is the 1.0 million-year-old Tieton Andesite, which advanced approximately 80 kilometers eastward down the ancestral Tieton and Naches rivers, and is the longest known andesite flow on Earth. Thick sections of flows with radial dips of 10-20 degrees surround the hydrothermally altered core of the volcano; the flows are cut by numerous dikes that define several sectors of a radial swarm. The Cispus Pass pluton occupies the southern part of the altered core and is questionable as young as 1 million years.
Geologists seem to have no difficulty accepting the fact that geological formations in the Cascades and elsewhere on earth are millions of years old, completely at variance with a "young earth" hypothesis. Do YEC's expect us to believe that all of these geologists are wrong?
The point of this thread should be the age of the earth based on geological formations, not a discussion of organic evolution, except as it may become necessary to further the topic.
A technical discussion of how the ages are arrived at should not be attempted, unless one is able to put the evidence into layman's terms. (This caution is, of course, subject to interpretation and flexibility, but common sense should prevail: if others here can't understand the point being made, it should be simplified or explained.)
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