Small pebbles are easily moved by the force of water.
Water is an erosive force that can create small, rounded stones and pebbles in mountain streams. Over time these stones are carried to the sea, where they can be deposited along with large amounts of sand. Does this Spark an idea?
Size
Although any size stone can be shaped by the force of flowing water, in general, the smaller the stone the more likely it is to be pushed towards the sea by the downhill flow of water. Therefore the stones and pebbles that get deposited in a river delta tend to be rather small. On a side note, if the delta area is located near large mountains, then the mouth of the river will receive many more rocks and stones than those places that lie at the edge of a large coastal plain.
Conglomerate
Over long periods of time, a sedimentary rock called conglomerate is formed, when small pebbles and stones of the of the river and seabed are glued together with the naturally occurring compounds of iron oxide, calcium carbonate or silica. The rock that forms looks like a mass of small stones stuck together. The most common piece of mineral in the mixture is usually quartz.
Practical Uses
Conglomerate does not have many practical uses except as a gift item. Still, the rock is actively collected and even mined in a few places like Australia, the United States and Ireland.
Tags: stones pebbles
