The Eparchaean Unconformity Tirumala hill

The Eparchaean Unconformity is a major discontinuity of stratigraphic succession in Tirupati-Tirumala Ghat road, which represents a period of the remarkable gap in the geological history of the Earth. This Unconformity separates the Proterozoic Gulcheru Quartzite and Archean granite representing a time gap of 500 Ma. The Geological Survey of India(GSI) declared the Eparchaean Unconformity “Geological Monuments of India”.

1. The Eparchaean Unconformity, in India that
missed 500 Million year time gap-A Geo
heritage site
The Eparchaean Unconformity is a major discontinuity of stratigraphic succession
in Tirupati-Tirumala Ghat road, which represents a period of the remarkable gap
in the geological history of the Earth.  This Unconformity separates the
Proterozoic Gulcheru Quartzite and Archean granite representing a time gap of
500 Ma. The Geological Survey of India(GSI) declared the Eparchaean
Unconformity  “Geological Monuments of India”.
Photo source-wikipedia.org

2. Silathoranam, a Natural arch, and a geological wonder are located in Tirumala
Hills at a distance of 1 km from Tirumala Venkateswara Temple. The Arch
measures 8 meters in width and 3 meters in height and is eroded out of quartzite of
Cuddapah Supergroup of Middle to Upper Proterozoic(1600 Ma) by weathering
agents such as water and wind.
Photo source-google.com
What is Eparchaean Unconformity
Tirupati Eparchaean Unconformity, a notified National Geo-heritage
Monument is a major discontinuity of stratigraphic significance that represents a
time gap of 500 Ma.in the geological history of the earth. This is due to the sudden
changes and discontinuity in the rock layers in the earth’s crust. It is seen at the
steep natural slopes and road scars in the Tirupati-Tirumala Ghat road in the
Chittoor district of Andhra Pradesh, India.

3. Photo source-Slideshare.com
The details provided by the GSI for the Eparchaean Unconformity monument
indicate that this feature forms the boundary surface between Proterozoic Gulcheru
Quartzite (Papagni Group) and Archaean granite.
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.

4. Photo source-Sliadeshare
Topography & Geology
The geological monument is located in the Tirupati valley, which is bounded
between The basin is delimited between the Palakonda-Velikonda and Sanambatla-
Srikalahasti and Nagari ranges of the Eastern Ghats. Tirupati Temple, the most
famous pilgrimage center in South India is in the midst of the range of hills. The
hills enclose the temple town to give it a form of an amphitheater setting.
Also, read- A forgotten Gossan-rich monument in India-The Rajpur-Dariba
Mineralised belt
The Tirupati hills are situated at the foot of a range of hills. There are four
geological units:
(1) Archaean rocks of the eastern Dharwar Craton (the granites and gneisses)
(2) the Eparchean unconformity (Quartzose sandstones overlying the granite with a
distinct unconformity)
(3) Puranas (a general name for Proterozoic sedimentary sequences found in a
series of basins  deposited on the Indian Shield; including the Cuddapah Basin)
(4) Quaternary deposits

5. Photo source-
Slideshare.com
The hill ranges of the Tirumala rise to a height of 900 meters. The steep scarp of
the ranges shows the Eparchian Unconformity’s topographic, structural and
denudational features. The sedimentary thickness of the Cudappah basin is of the
order of 12 kilometers and includes volcanic sequences in the form of sills and
dykes.
A prominent Eparchaean Unconformity of the formation resting on the
archaean peninsular gneissic complex is noted. Rocks of the Cuddapah
Supergroup, and the overlying Kurnool Group, comprise the stratigraphic sequence
of the basin. This feature is contiguous all along the defined Archaean-Cuddapah
contact zone even though its age may vary along its traced path.

6. Photo source- Slidesahre.com
Geological Monument is well connected by road, rail, and air routes. The nearest
railhead to Tirumala hills in Tirupati. The geological monument is located 10
kilometers northwest of Tirupati town, at the 12 kilometers point on the Tirupati-
Tirumala Ghat road.