sedimentary

Conglomerate (rounded-pebble rock)

Lithified polymictic conglomerate; clasts cemented by a finer mineral matrix

AI-generated identification · may be incorrect

Rounded to subrounded, pale cream and gray clasts in a tan matrix; likely quartz- and feldspar-rich, though exact minerals cannot be confirmed from the photo. Hardness varies with the clasts and cement; texture is coarse and visibly heterogeneous, with no consistent cleavage or crystal structure.

Identified September 30, 2026More sedimentary →

Explore Conglomerate (rounded-pebble rock) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed when rounded gravel was deposited by energetic water, then compacted and cemented; age and precise depositional setting cannot be determined visually.

Uses & applications

Primarily a teaching and collecting specimen; conglomerate is also used as dimension stone or aggregate where sufficiently strong and abundant.

Geological facts

The rounded fragments indicate transport and abrasion before burial, unlike the angular fragments typical of breccia.

Field identification & locations

Look for distinct rounded pebbles larger than 2 mm embedded in a finer matrix. Similar rocks occur in ancient river channels, alluvial fans, and beach deposits worldwide.