History of Indian Natural Stone
Stone is old, older than human, older than human life itself. Baked in the earth’s furnace, shaped by geographic events going back millions of years, the stone is the building block of civilization, the foundation on which a culture stands. Humankind’s greatest creations, its monuments, statues, and sculpture are the story of absolute command over the stone.
If the Taj Mahal is termed as a heritage, so is the marble that it comprises, quarried at the Makrana mines, 375 kilometers west of Agra. While the Taj is a Unesco World Hertitage Site, Makrana is hollowed earth, a landscape peppered with stone crushers.
Modern Usage of Indian Natural Stones
Even today, with the discovery of new materials and advanced techniques, it seems that stone still has a firm place. The present building materials choices are cement and ceramic along with bricks. One of the underlying reasons is that concrete is strong and can be molded in many ways much more easily as compared to stone. It is much more portable is especially suited to large structures like dams and reservoirs. However, it is no surprise that the base for cement and concrete is still stone, which is being mixed with cement to produce concrete.
In turn, cement is made with powdered limestone mixed with gypsum. Concrete is far less robust than a stone with a maximum life of 100-150 years, which is tiny compared to the temples and forts built thousands of years ago and still standing tall.
Stone as a considerably stronger and durable construction material is one of the main reasons for its growing recognition across the world as compared to brick-and-mortar.
Stone continues to remain connected to our lives to date. In India, wherever there is the abundant availability of stone, it is the foremost choice of roofing, paving, and even wall-building along with cement as grouting.
Northern and Southern Indian Natural Stones
In northern India states like Rajasthan, UP and MP, sandstone and slate are still considered as economical materials for building homes, both as paving and roofing material. They are very durable and need almost negligible upkeep.
In the southern side viz. In Andhra Pradesh and some parts of Karnataka, limestone, and slate are used in urban or rural areas, as the cheapest building material as it is easier to cut into slabs and stack up together. In the coastal areas, especially in southern India, laterite is the preferred option of building substance. It is a variety of granite that is weathered down more compared to other forms and is lighter as a result. This makes it portable and also easy to chisel and cut into slabs.
Geological details of Indian Stones
India has had a dimensional, ornamental, and sculptural stone in various temples and monuments over numerous decades. The number of types and sub-varieties would be in hundreds.
The Indian subcontinent’s material civilization is well engraved in stone sculptures that cover a period of five thousand years—the oldest sculptures found in Mohanjodaro and Harappa date to the third millennium BCE.
The gradual accumulation of knowledge of using natural stone also comes through in the architecture of temples, mosques, minars, stupas, rock-cut caves, and forts. There are 32 World Heritage Sites in India recognized by UNESCO, of which 25 are cultural sites and seven are natural sites.
India also has diverse geology with different rock types representing the complete spectrum, from some of the oldest Archaean metamorphites/granitoid to the youngest Quaternary alluvium.
Geologists broadly divide the Indian subcontinent into three domains: peninsular India, extra-peninsular India, and the Indo-Gangetic-Brahmaputra plains. The Indo-Gangetic plain lies between the shield area—the mountains of peninsular India south of the Arvallis and Vindhyas and the Himalayas of extra-peninsular India, comprising essentially the younger meta-sediments formed comparatively recently on a geological time scale when the Indian subcontinent separated from the African landmass and collided with the Asian landmass.
The heritage sites located in different geological provinces provide unique natural stones to cultural sites that are marked by their brilliant craftsmanship. In general, the formation of granite and basalt started 4.8 billion years ago, whereas the formation of other stones has been happening since, till 500 million years back. Earth’s waters have corroded much of the rock into vast plains, like the north Indian plains.
It is now considered that all dimension stone types may be a “potential heritage stone”. Publications of all types that describe, discuss and promote nominated stone types have been invited by HTSG. The geologists have since been focusing on preparing and approving GHSR nominations and planning to eventually promote community recognition of the designation, protecting recognized GHSRs, and revising the existing heritage status of designated stones.
A geological province is a geological area that developed in considerable isolation from its neighbours over millions of years and exhibits unique properties in the stones and rocks found within it. Dimension stone can be defined as natural rock material quarried for the purpose of obtaining blocks or slabs that meet specifications like width, length, thickness and shape. Colour, grain texture and pattern and surface finish are also normal requirements. Durability based on mineral composition and hardness and past performance, strength, and the ability of the stone to take a polish are other important selection criteria.
The Indian subcontinent sits on five major cratonic zones or rock foundations whose base developed from massive lava flows in the Archaean period—4.8 to 2.5 billion years ago—also considered the age of the earth. The lava flows over time formed into granite, basalt, and later different forms of sedimentary rocks.
Sediments form in many ways, for example, sandstone is a solidified form of sand and similar sediments. Clay forms into shale and later slate when climatic conditions force it to harden under pressure. Marble, on the other hand, is formed from the metamorphosis of limestone, which in turn collects in deep sea beds over millions of years. A prime example of this is limestone found on top of Mount Everest, showing it originated in deep-sea and was forced up by tectonic activity. This is also the reason the
Himalayas are earthquake prone and the stones found are predominantly limestone since they were formed quite recently in terms of geological time.
The north and the northwestern geological region is considered the largest in the Indian subcontinent, extending from the peninsular Vindhyan ranges to the extra-peninsular Himalayan belt. It is also the most important province housing several heritage monuments, from Kashmir to Bundelkhand and Rajasthan to further east up to Kolkata where the Victoria Memorial, built from Makrana marble, stands. It extends from the areas of the Son and Tapi rivers in the south in Bundelkhand which houses the Bundelkhand cratonic belt that separates it from the areas further south. It includes areas now in Pakistan and the Aravali-Delhi ridge which is where Rashtrapati Bhavan is located, the Vindhyan Mountains, and the Trans-Aravali Vindhyan supergroup rocks.
The Vindhyan supergroup is one of the largest and thickest sedimentary successions of the world showcasing the varied facets of Proterozoic geology, 2.5 billion to 500 million years ago. The region also forms the northern border of the Indian subcontinent and is occupied by the extra-peninsular region of the Himalayan mountain ranges.
Indian Limestone – Origin
Slates and limestones are natural stones largely used in construction and housing in the northern ranges of this region due to their ready availability in the Himalayan rock formations. The temples of Awantipur, built in the 8th and 9th centuries in Kashmir are made up of dark-colored Triassic-era limestone which has weathered over time. Kangra Fort in Himachal Pradesh, on the other hand, is founded on boulders with sandstone slabs while the rest of the construction, of limestone, has been subject to easy decay by natural processes.
Similarly, the group of carved rock temples at Masrur in HP, a heritage site, are now in a critical state owing to various processes of natural decay, earthquakes, and climatic conditions. The site lies close to the active Himalayan seismic belt and has been subject to deformation by earthquakes, like the Kangra temblor of 1905.
Limestone from this region is also extensively used in construction sites and for other purposes, which makes conservation and recording processes of different types of this stone a matter of priority.
The sedimentary rock base to the south has been a huge resource for heritage stone in ancient as well as recent construction and building materials. The Vindhyan supergroup covers an area of about 1.04 lakh sq km and can be considered a Global Heritage Stone Province in the northern and northwestern provinces of the subcontinent. Its rocks are un-metamorphosed and have undergone only minor tectonic deformation unlike further north around the Himalayas.
Indian Sandstone – Presence
Sandstone, a traditional building material, has been used in many historical monuments and is still used in construction today. Rashtrapati Bhavan, for instance, is a sandstone construction. The stone also offers varied colors which are due to the presence of different elements during the period of metamorphosis; this adds to its aesthetic qualities. The dominant stone used in this region is Vindhyan sandstone; indeed it is the main construction material across north India since ancient times and is at the top of the stone export list today. Even sculptures in this region, from 400 BCE, are carved from sandstone. Its comparative softness and the ability of some types to take on a high polish are highly prized.
A classic example is the Lion Capital of Ashoka, circa 250 BCE, of four Indian lions standing back to back, carved from a single block of polished sandstone and adopted as the emblem of the government of India. The Buddhist monuments at Sanchi, circa 200-100 BCE with a plethora of pillars, palaces, temples, and monasteries in different states of preservation, are another brilliant example.
The Brihadeswara temple in Thanjavur uses various grades of local granite.
The rock caves of Bhimbetka, in sandstone, comprise a group of five clusters of rock shelters with paintings that are part of the Khajuraho group of monuments. The temples of Khajuraho are an example of the fusion between sculpture and architecture, captivating erotica bringing out human sentiment through sandstone engravings. The temples of Khajuraho built by the Chandela kings in the 10th and 11th centuries are considered monumental works the world over.
About 30 temples were constructed in a period of 100 years. Khajuraho sandstone belongs to a sub-group of the Vindhyan supergroup. It is generally fine-grained and considered excellent building material and found in various shades of buff, pink and pale yellow.
Interestingly, the geological foundation of the temples is granite but the building stone was quarried from the banks of the Ken River which flows close to the site with the temples built over the strong granite base. In many temples granite as sculpted material has been used although sandstone dominates. The minuscule partings, weathering and incipient joints in the sandstone show the ravages of time and climate, with decay, breakage, parting and defacing of the sculptures.
The medieval period, dominated by the Mughal Empire that extended from 1525 to 1860, expanded on the traditional Persian styles of sculpting and architecture to create palaces, mausoleums, and fortresses of stone ranging from white marble to red sandstone. The most prominent utilization of both together is at Humayun’s Tomb (1569) where red sandstone is externally decorated by marble borders and panels. Later the Red Fort built in the 17th century, Agra fort and Fatehpur Sikri became classic examples of natural stone of the Vindhyan supergroup, marble usage peaking with the construction of the Taj Mahal.
The Makrana quarry is at the eastern margin of the Thar desert and has an ancient mining history since the stone displays almost no deviations in color. It is the top source in the marble industry because of the ease with which it can be cut into blocks, whiteness, high calcium content compared to lower levels of degrading minerals, high polishing potential, and luster. The translucent varieties of Makrana marble are preferred over others for monumental and sculpture work. Its deposits occur in five prominent rock bands or stretch in the area west of Makrana.
Sandstone used in various heritage buildings is also found in the Marwar supergroup or Trans-Aravali region, which is a separate geological entity due to its different time of formation. Marble from here is generally fine-grained, buff-colored, hard, compact, and is also considered a good quality dimension stone used in forts and other buildings in the north and western India.
Marwar is among the many Proterozoic sedimentary basins that developed in peninsular India that preserve rich records of geological history. Its formation is considered to be later than the Vindhyan although some of the regions of activity overlapped.
The Jaisalmer region, on the other hand, has large reserves of buildings and ornamental stone in the desert country. The rock formations exposed around the fort area consist of a thick sequence of cream, buff, and brown colored limestones and grayish, brownish-yellow sandstone. The fort, one of the world’s largest fully preserved fortified cities, is also a World Heritage Site in the sandy expanse of the Thar Desert.
Built-in 1156 AD, the fort has sandstone and a peculiar, bright yellow variety of limestone, with a fine-grained texture and good polishability. It is one of the top contenders for GHSR. This yellow limestone has been mined for centuries. Being abundant and easy to mould it is used extensively for construction even today.
The present trend is to make stone carvings, both hand-sculpted and machine-sculpted. Architects promote items made of sandstone and carved materials in residential villas, which has helped revive centuries-old stone craftsmanship in the region. Apart from Rajasthan it is widely available in Madhya Pradesh as well, in red, buff, beige, pink, etc., fetching huge amounts in international markets.
Basalt stone – Origin
South of the Vindhyan region, the Deccan plateau and the larger region referred to as the Deccan Traps consists of massive stacks of multiple layers of solidified basalt that flooded and occupied the larger west-central region. The layers of basalt form a crust more than 2,000 metres thick and cover an area of 5 lakh sq. km. This basalt is the source of construction material for some of the most pectacular monuments, including the Ajanta and Ellora temples, both World Heritage sites. Lava flows in this region have been nearly horizontal, which allowed the sculptors to chisel the rocks from top down.
The practice of creating a structure by carving it out of natural rock was well developed in this region and these caves were achievements of both structural engineering and craftsmanship. The Deccan Traps covers almost all of Maharashtra, part of Gujarat, Karnataka, Madhya Pradesh and Andhra Pradesh marginally.
It is said to have formed when the Indian subcontinent plate was moving through the volcanically active Reunion hotspot in the Indian Ocean millions of years ago. Basalt masonry blended with sandstone from some areas like the Gondwana group of rocks have been extensively used in heritage structures like the Gateway of India and the Chhatrapati Shivaji Terminus in Mumbai.
Granite – Origin
The region south of the Deccan Traps, referred to as the southern peninsular region consists of Proterozoic-era rocks. They are predominantly granites and gneiss which is comparatively weaker. A majority of the rocks are much older than the northern regions of the subcontinent and were formed by thick lava flows as a result of extreme tectonic activity. It has two sub-regions, the northern part abutting the Deccan Traps known as the Dharwar region. The southernmost part, known as the southern granulite region, is separated from the Dharwar region by the Palghat-Kaveri shear zone, which refers to a time-gap in the formation of the two regions.
The southern granulite region is made up of differently formed granulites, charnockites and khondalites, which got the name because that particular rock is found in Phulbani district of Odisha dominated by the Khond tribe; similarly, charnockites get the name after the Englishman Job Charnock (founder of Calcutta) whose statue was found to have been carved from this distinct stone. These rocks have been used in the construction of heritage buildings, temples and other constructions through millennia.
The southern kingdoms successively show many fine examples of sculpture from various granites and gneiss, charnockites and khondalites which are widely available in the region and still used locally as well as being exported.
The Konark temple of Odisha is an example of khondalite found mostly in this region and in some parts of Burma. Khondalite is a type of gneiss found in the Eastern Ghats coastal region and prone to weathering and chemical alteration, a major factor in the gradual disintegration of the stone used in the temple. The temple complex is built of khondalite on the bed of the river Chandrabhaga over a thick pile of boulders and sand with no other solid foundation. The temple is in various shades of brown, yellow, and other colored stones.
In temples, stupas and other monuments stone provided the strongest option because of its durability since it was intended to mark the infallibility and remembrance of its builders. With patronage and investments from rulers, rarer stones also came into use. In the Taj Mahal, for example, lapis lazuli has been used for ornamental engraving in turquoise blue. It was imported from Iran and Italy. Granite and marble were used for statues because of their fine polishability while metal became the preferred choice with the development of exquisite metallurgical skills, especially in southern India.
The Mahabalipuram shore temples, classified as a World Heritage Site, were constructed under the Pallava dynasty in the 7th and 8th centuries. Each temple is carved from a single rock with all known plans and elevations incorporated through chiseling and craftsmanship. The Pallava rock-cut temples with finely carved sculptures use reddish granites and charnockites, considered among the hardest and most durable of rocks, yet amenable to fine sculpting.
Granite structures at the Meenakshi temple in Madurai and Hampi in Karnataka made use of the surrounding rocks. Chola temples of the 11th and 12th centuries at Thanjavur are considered architecturally the most ambitious granite structures. The monuments at Pattadakal have also been made from the granites of this peninsular shield. Today’s surviving Chola temples, including the three temples of Brihadisvara, Gangaikondacholapuram, and Airavatesvara at
Darasuram of the 11th and 12th centuries have been declared World Heritage Sites. The different types of granites from this region have been used for centuries in monuments and have had other important uses, too.
India has one of the biggest reserves of granite, with almost 200 colours and textures. More than 20 per cent of the world’s granite is found in India and mostly in Tamil Nadu, Karnataka and Andhra Pradesh, with Tamil Nadu holding 75 per cent of the trade share. More than 150 units produce and export various shades of the stone. Indian granites are the most sought-after and extensively used material in construction and structural works throughout the world. That makes recognition and record-keeping of these GHSR-hopefuls vitally important in light of the burgeoning export and probable disappearance of some particular forms.
The eastern and northeastern regions of the subcontinent, including present-day Bangladesh, can be classified as a sub-region with a different set of stones used for various purposes. Separated by a geological region called the Mahanadi rift, where there is a considerable gap in the ages and formation processes of the two portions, the region includes Singhbhum, Chhotanagpur and Meghalaya as well as areas further east. But there is comparatively little use of natural stone in temple complexes such as the Mahabodhi complex at Bodh Gaya, also a World Heritage Site.
It is one of the four holy sites related to the Buddha and so has universal importance which makes preservation and development of the area’s stone art almost mandatory. While this was the first temple built by Ashoka in the 3rd century BC, the present complex was built in 500-600 AD and encompasses the best remains of the time in the subcontinent. It is built entirely in brick with clay mortar and coated with lime and considered the best-preserved example of brick architecture in India from this particular period.
It is considered to have had a significant influence on the development of brick architecture over the centuries. The use of natural stone is limited to granite slabs as floor and sandstone in the railings, though it is presumed their use in the original temple was more widespread. The granites used are available in the region while the sandstone belongs to the Vindhyan region available only at a considerable distance. The temple has undergone repairs and restoration on several occasions.
The Victoria Memorial in Kolkata was built between 1906 and 1921 to commemorate Queen Victoria’s reign in India. The white-marble structure was made from natural stone brought from Makrana.
“India is endowed with high-quality natural stones with exotic varieties of granites, marble, sandstone, etc. In view of their historical, cultural, and architectural importance these natural stones deserve to be considered as potential GHSRs. The historic importance is (already) recognized for Vindhyan sandstones, Makrana marble, and peninsular granites. These heritage stones not only achieved widespread utilization in the cultural history of India but (were) also used in many architectural masterpieces; hence they deserve designation as potential GHSRs.”