#metamorphicmonday — Public Fediverse posts

Boudinage

Boudinage are one of the most spectacular geologic structures and some of my favorite rocks. The boudins are the eye-shaped lenses of rock wedged between the white quartz layers. Find out how they formed below.

Callan Bentley's great AGU blog post on boudinage explains it all: https://blogs.agu.org/mountainbeltway/2011/06/20/boudinage-favorite-geoword/

More beautiful boudinage here: https://goo.gl/XXSyEv

Image from: https://folk.uib.no/nglhe/PhotoAlbum/Boudinage%20Chapter%2014/index.html

#boudinage #metamorphism #rocks #geology #MetamorphicMonday #ScienceMastodon

Mount Laurel "Roof Pendant"

The volcanoes, whose inner-most workings are exposed in the granitic rocks of the Sierra Nevada, transformed the ancient sediment layers into which they were intruded. Erosion later isolated the remnants of the metamorphosed rock, suspending them above the granite as "roof pendants." The folding of these layers is most dramatically illustrated at Convict Lake when the lighting is just right. Click on the photo to below to expand.

"The story of the mountains around you began half a billion years ago when sand and gravel washed off an ancient continent and built up in layers beneath a vast ocean. Changed by extreme heat and pressure, most of these rocks have eroded away, but some remain.

Embedded within them are fossils of organisms that lived in the ancient sea and are some of the oldest rocks in the Sierra Nevada Mountains.”

#geology #RoofPendant #MountLaurel #ConvictLake #MetamorphicMonday #ScienceMastodon