BRECCIA

Colour: Variable.

Texture: Consists of angular rock fragments (2 mm to many metres in diameter) set in a fine- to medium grained matrix. In some breccias the fragments can be seen to match along their opposed sides, indicating only modest disturbance.

Structure: Bedding not usual, though in some types of breccia bedding is apparent in the matrix. Fossils rare.

Mineralogy: The fragments may be of any type of igneous, metamorphic or sedimentary rock. The matrix usually consists of silt or sand cemented by calcite or silica.

Field relations: Many breccias represent consolidated talus or scree material, that is accumulations of rock fragments formerly lying on steep hill slopes, or at the foot of cliffs. They are often found above uncomformities, and associated with conglomerate, arkose and sandstone. Other breccias are produced by the fragmentation of rocks during faulting." (Hamilton et al 1976, 192)

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