Puddingstone (rock)

The rounded pebbles and the sharp contrast in colour gives this type of conglomerate the appearance of a raisin or Christmas pudding.

Hertfordshire puddingstone is a silica-cemented conglomerate composed of rounded flint pebbles and cobbles with matrix of fine sand and silica cement.

The Hertfordshire Puddingstone is characterized by silica-cemented flint gravel that is brown to deep red in colour and often exhibits black exteriors and thin rinds on cut or polished surfaces.

It typically occurs scattered across the land surface as isolated concretion-like masses in the areas of Hertfordshire and Plumstead Common, England.

[5][6] Pieces of Skunnemunk Conglomerate are easy to recognize and have been found in glacial deposits throughout the lower Hudson Valley region.

This conglomerate is composed of a grey feldspathic sand matrix and well-rounded pebbles and cobbles of quartzite, granite, felsite, and quartz monzonite.