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Conglomerate is a type of rock which contains variously sized rounded stones embedded in a matrix of sandstone.

It is often formed in desert climates, when sudden storms result in flash floods. These sudden intense events shift large quantities of sand, pebbles and boulders, which are then dumped as the water recedes, dry out and are eventually lithified to form a conglomerate or puddingstone.

There can be repeated such events over thousands or millions of years, resulting in deposits hundreds of metres thick, often in fans radiating outwards from where the flashfloods emerge from a gully or wadi.

What is now Scotland was desert during the Devonian period between 490 and 353 million years ago, when it lay at roughly the latitude of the present Kalahari Desert. Most of the conglomerates in Scotland were laid down in the Devonian.

Later on continental drift brought Scotland to the latitude of the Sahara Desert during the Permian and Triassic periods, between 290 and 205 million years ago. The New Red Sandstone is Permo-Triassic in age.