sedimentary

Conglomerate

AI-generated identification · may be incorrect

Coarse-grained clastic sedimentary rock composed of rounded to subangular gravel-size clasts (> 2 mm in diameter) set in a finer-grained matrix of sand, silt, or clay, and cemented usually by calcium carbonate, iron oxide, silica, or hardened clay. Hardness varies depending on the clasts and cement.…

Identified July 23, 2026More sedimentary →

Explore Conglomerate 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 by the accumulation and lithification of rounded rock fragments (gravel, pebbles, cobbles) transported by water, ice, or gravity, typically in high-energy environments like river channels, beaches, or alluvial fans. The rounding of the clasts indicates significant transport distance or abrasion before deposition.

Uses & applications

Often used as a construction material, as aggregate for road building, or sometimes cut and polished for ornamental purposes if the matrix is strong enough.

Geological facts

Conglomerates are distinguished from breccias, which are composed of angular clasts. They often represent ancient riverbeds or shoreline deposits, providing valuable clues about past sedimentary environments.

Field identification & locations

Identified by its visible, rounded to subangular pebbles or cobbles embedded in a finer matrix. Common worldwide in areas with past or present high-energy sediment transport systems.