Eparchaean Unconformity
Coordinates: 13°41′00″N 79°21′00″E / 13.6833°N 79.35°E
Eparchaean Unconformity (Tirupati hills) is a major discontinuity of stratigraphic significance that represents a period of remarkable serenity in the geological history of the earth. It is seen at the steep natural slopes, road scars and ravines in the Tirupati – Tirumala Ghat road in Chittoor district of Andhra Pradesh, India.
In 2001, the Geological Survey of India (GSI) declared the unconformity to be one of the 26 “Geological Monuments of India”. GSI's commemoration document, published on the occasion of the 150 years anniversary celebration, provides an insight into the formation of the subcontinent, the orogeny, the paleoenvironment and the exotic collection of paleo-flora and fauna. The details provided for the Eparchaean Unconformity monument indicate that this feature forms the boundary surface between Proterozoic Nagari Quartzites and Archaean granite. The time gap between the formation of the two units is at least 500 Ma.
At this location, the boundary is between sedimentary rocks of the Cudappah Supergroup, 1600 million years in age, and Archaean rocks comprising granites, gneisses and dolerite dykes that are more than 2100 million years old. This unconformity gives an indication of the enormous time gap in the creation of the earth’s crust.
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