Here's why:

* Sand and Pebbles: The mixture of sand and small pebbles are the sediments that make up the rock.

* Cemented Together: The sediments are held together by a cementing agent, which is usually minerals like calcite or silica. This cementing process happens over time as water carrying dissolved minerals flows through the sediments.

Conglomerate is a type of sedimentary rock, formed from the accumulation and cementation of sediments.