The Deformation of the Bar Conglomerate

The basal Delhi conglomerates seen at Bar are reputed for the intense deformation seen in them. Heron's memoir on central Rajputana contains a brief description of these conglomerates.

The pebbles in the conglomerate are mostly made up of quartzites. They vary in size from small pebbles to large cobbles. The percentage deformation in the long axes of the pebbles is around 175, and in some extreme cases about 700. The pebbles lie in the cleavage/bedding surface with their long axes almost parallel to each other. The long axes are coincident with the true dip of cleavage surface.

The overall matrix of the conglomerate is psammo-pelitic and consists of sharply alternating psammite and pelite layers. A strong cleavage is seen in the matrix which is parallel to the bedding.

The pebbles are in all cases flattened and elongated. A two stage deformation model in which an early phase of flattening followed by flow is suggested for the pebbles in the conglomerate.