Author Question: Compare and contrast fissure eruptions and pyroclastic sheet ... (Read 42 times)

mspears3 · **on:** Jul 13, 2018

Compare and contrast fissure eruptions and pyroclastic sheet deposits.

Question 2

Which orogeny was the first pulse of mountain building in the Appalachian mobile belt?
A)Caledonian
B)Acadian
C)Antler
D)Ouachita
E)Taconic

honnalora · **Reply #1 on:** Jul 13, 2018

Answer to Question 1

During both fissure eruptions and pyroclastic sheet deposits, eruptions issue from long cracks or fissures, cover vast areas, and volcanoes fail to develop.

During fissure eruptions, the lava is so fluid (has such low viscosity) that it spreads out and covers vast areas.

In contrast, it seems that pyroclastic sheet deposits originated as pyroclastic flowshence the name. The pyroclastic materials of many of these flows were so hot that they fused together to form welded tuff. Geologists now think that major pyroclastic flows issue from fissures formed during the origin of calderas.

Answer to Question 2

E