Conglomerates and disconformities, described below, are both erosional surfaces. They are distinguished here on the basis of particle size. A conglomerate contains pebbles, or even boulders, whereas a disconformity is simply a boundry between two typical sandy limestones (of substantially different age).
On rocky erosional shorelines there may be isolated accumulations of rock rubble dislodged by the sea. These coastal accumulations, known as conglomerates, have contents which are diagnostic of their marine origins, such as well rounded fragments and marine skeletal debris. Dispite their scarcity and limited extent, conglomerates of Pleistocene age are important pieces of evidence on previous high sea levels; particularly so if they are associated with a biogenic notch or contain pieces of coral which can be dated.
In Bermuda, a disconformity is a boundry between geological
Formations which is equivilent in time to a paleosol, but at which the
paleosol is absent. The interval of erosion represented by the disconformity
accounts for the removal of the paleosol. A likely scenario for the formation
if a disconformity would be coastal erosion followed by deposition of marine