NPS home USGS home USGS/NPS banner

Visual Glossary

Flattened rock with foliation versus stretched rock with lineation.
Flattened rock with foliation versus stretched rock with lineation. Illustration by Anne Crowder.

Foliation

spacer image Foliation forms when pressure squeezes flat or elongate minerals within a rock so they become aligned. These rocks develop a platy or sheet-like structure that reflects the direction that pressure was applied in. Slate, schist, and gneiss (pronounced 'nice') are all foliated metamorphic rocks.
Folded gneiss. spacer image It’s not hard to see that this metamorphic rock, called gneiss, has been foliated, then intensely folded. Photo by Edward P. Klimasauskas, USGS.
horizontal bar
| USGS Geology in the Parks home | NPS Park Geology Tour home |

This site is a cooperative endeavor of the
US Geological Survey Western Earth Surface Processes Team
and the National Park Service.

Please share your comments and suggestions with us!
parkgeology@den.nps.gov

http://www.nature.nps.gov/grd/usgsnps/deform/gfoliation.html
This page was last updated on 9/7/00