Author Question: How do the eruptions that created the Columbia Plateau differ from eruptions that create large ... (Read 47 times)

debasdf · **on:** Jul 14, 2018

How do the eruptions that created the Columbia Plateau differ from eruptions that create large composite volcanoes?

What will be an ideal response?

Question 2

What type of volcanic structure is Shiprock, New Mexico, and how did it form?

What will be an ideal response?

beccamahon · **Reply #1 on:** Jul 14, 2018

Answer to Question 1

The Columbia Plateau eruptions were fissure eruptions of fluid basalt rather than violent pyroclastic andesitic eruptions. The flood basalts flow outward and form large flat plateaus rather than building tall conical structures.

Answer to Question 2

Shiprock is a volcanic neck. When a volcano becomes inactive, congealed magma often becomes preserved in the feeding conduit of the volcano as a crudely cylindrical mass. Over time, all volcanoes will succumb to forces of weathering and erosion. Over time, the rock occupying the volcanic conduit, which is highly resistant to weathering, may remain standing above the surrounding terrain long after the cone has been worn away.