The Dynamic Earth View Multimedia Version

Main Menu >  GeoGallery >  Rocks >  Dacite
TITLE: GeoGallery

Choose one of the following Rocks for more details:

Breadcrust Block

Breadcrust Block

This block was still hot when it rolled down the growing lava dome. The surface cooled and solidified, but hot gases expanded inside until the crust cracked. Baking bread cracks the same way: hence the name, breadcrust block.

Breadcrust Block

Breadcrust Block

This dacite block tumbled from the growing lava dome in Mount St. Helens's crater. After the crust hardened, gas continued to expand in the partly molten interior, swelling and cracking its surface like bread when it bakes.

Dacite

Dacite

This is a small piece of a dump truck-sized lava block. It was carried down the volcano's flanks by a roiling mudflow on May 19, 1915. Days after such blocks came to rest, many were still too hot to touch.

Dacite

Dacite

This is a small piece of a dump truck-sized lava block. It was carried down the volcano's flanks by a roiling mudflow on May 19, 1915. Days after such blocks came to rest, many were still too hot to touch.


bottom navigation bar Smithsonian National Museum of Natural History Department of Mineral Sciences website Credits