SANDSTONE
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Ok, back to School!
So what exactly is sandstone?
Basically, a sedimentary rock made up of grains of silica (quartz) sand that have been compressed and cemented together, in this case in a shallow seabed that existed here many millions of years ago.
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You can't make out the individual grains of sand that make up sandstone from a distance but you can feel its distinctive gritty texture when you run your nail along it.
Viewed up close with a hand-lens
you can see how grains of silica have been 'sorted' by size before being cemented together.
Jodhpur’s sandstone, locally called 'chhittar', is mostly seen in beige tints, or, to be more precise, in Tuscan Brown (R250-G214-B165)
Chhittar can be delightfully wayward with swirls of dark minerals on a pale ground and often striped with slanting bedding marks that can look remarkably like salmon flesh.
Golak and I were able to watch traditional craftsmen at work because some part of Mehrangarh is almost always being restored or enhanced. We saw, for example, Jodhpur’s craftsmen using a chiselling technique to score dots or lines on a smooth stone surface. Depending on the intensity and angle of their chisel-blows (called chôte, which translates as ‘bruise’), this technique yields patterns called tachaee, matthaee or gaddhaee. It looks folksy and spontaneous, with no effort at creating measured uniformity.
And the effect is lovely!
Traditional ways of treating sandstone surfaces in Jodhpur are either about smoothening it out or – what may seem counter-intuitive but is actually very clever – making it even rougher, but in a measured, artful way.
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Zenana Deodi courtyard high up in Mehrangarh
At Soorsagar’s mines it was easy to see why sandstone is always used for built structures in and around Jodhpur. Because of its abundance it is significantly cheaper than brick. It can be split, cut and shaped with ease, cleaving to the chisel like a dependably obedient material.
Traditional workmen have developed niche skills and a vocabulary of special terms in their own language for the many ways in which they have worked sandstone for centuries.
Jodhpur’s craftsmen are particularly good at carving it, and Mehrangarh Fort, with its Rajput blend of rugged immensity and finely carved tracery, is an excellent example of the versatility and tractability of sandstone.
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(LEFT) This is the old, but now completely outmoded, way of splitting sandstone in Soorsagar's mines. The man wielding a hammer at the end of 6-foot long shaft strikes his pegs with unerring aim!
This method of cleaving sandstone along bedding planes has been replaced by a nose-wrinkling procedure where a noxious white powder is poured into drilled holes, which splits the rock as the chemical substance expands.
Singhoria Pol is made of very large blocks of sandstone beautifully fitted together. Our first inter-vention was to punch away the bricked-up entranceway as well as the blocked arches on the first floor to recover their original form.
A little sandblasting achieved a nicely renewed surface on the outside and for our kaarigars (stonemasons) it was a straightforward job of first replacing all the worn out floor-slabs and then chiselling patterns onto them using traditional techniques of tachaee.
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Our first thoughts about using sandstone turned to ways in which tall, slim slabs – called chheeniya – are used in the countryside.
When you travel outside Jodhpur city, you can’t help noticing that the most common kinds of boundary walls are made of 8-foot tall chheeniya planted upright, close together. They are often strikingly attractive with swirls of earthy colours, but by this time we had decided on stacking up rhyolite boulders for our boundary walls and time spent in Soorsagar’s mines was now all about looking for chunky blocks of sandstone for making things like table-bases.
Cheeniya boundary wall
GOLAK KHANDUAL:
Pradip wanted an outdoor coffee sitout and I started to think about permanent garden furniture in stone. I knew I didn’t want to use readymade rectangular blocks of sandstone – they’re much too regular and industrial-looking. So we started exploring in the quarries, looking for hewn stone that had not already been sized into big blocks.
And then one day – perhaps on our second or third day exploring in the quarries – we looked down at our feet and had our first ‘Aha!’ moment.
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RIPPLES IN SANDSTONE
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We found ourselves standing on a striking pattern of 'ripple marks' sprawling across the floor. No one other than Pradip and I seemed to think it was in any way unusual or special. The rippled surface was being walked upon, machines were being dragged across it and we felt like shouting out, “STOP! You’ll scratch these beautiful patterns!”
It was clear that surfaces like this were neither unusual nor much valued.
It may have been the slanting rays of the winter sun that morning, but it felt like an optical illusion. Perhaps it was just the sheer elegance of a wide stretch of naturally formed ripples. In that first glimpse, both of us could see how it might make a gorgeous surface in a designed hardscape.
I felt we needed somehow to carry away fairly large slabs of rippled sandstone if we wanted to recreate anything like the impact this floor had had on us. I wasn’t sure how feasible this would be.
“Ask them if they can give us some of this floor,” we said to our park supervisor, Devinder. He rubbed his chin and looked a little helplessly at assistant engineer Najeeb, as if to say, “See what they’re asking me to do!”
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They spoke to the muneem at the mine in low tones like they were negotiating a shady deal. In the end the muneem shook his head.
“Can’t be done,” he said. “It will break into pieces if we try and take it out… Better go look in some other mines. You’ll find LOTS of these ripples! They’re common.”
In the mines they call rippled sandstone lahariya bhaakad. Wavy rock.
The muneem was right. It is common. We must have visited 40 or so mines and saw rippled sandstone nearly everywhere we went, but only in small, cut sections.
Ripples in Sandstone are basically vestiges of a shallow, sandy beach that has turned to stone.
Think of Ripples like this:
as waves surge on the surface, the sandy surface of a shallow seabed is pulled gently back and forth, creating the ripples you see when you look at a shoreline. It only does so upto a certain depth, below which the sand on a sea- or lake-bed is unaffected by the pull of the waves.
Then something changes –
a sea recedes, a shoreline is exposed and is eventually covered by more silty sand or mud. And then, and only in certain circumstances, as they are compressed by the weight of sediments on top, the ripples below turn very slowly to stone.
Each set of ripples is thus a unique record of the conditions that created them – the combined effect of the wind and tides and the shape and disposition of the beach itself.
Scientists who study sedimentary rocks can actually tell with remarkable precision how different patterns – such as 'tuning-fork', 'linguoid' or 'sinuous' ripples – correspond to how the wind or tides were behaving when the beach first dried up millions of
years ago.
We wanted bigger, raft-sized slabs like this one
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Sandstone is mined from horizontal layers that may have built up at some depth.
Every now and again, you’ll find a slab of ripples that represents the top (or bottom) of a sedimentary ‘event’ that took place millions of years ago.
So at intervals that are neither regular nor predictable, rippled surfaces are exposed and dug out in the mines.
Because they’re quite common, no one in Jodhpur seems to pay them more than passing attention. You will often come across ripples in small, random bits of flooring and walls in Jodhpur as if it’s only a variation of ‘normal’ sandstone – which of course it is!
You can see here how the UNDERSIDE of a sandstone block has been impressed with a mirror image of the ripples that lay below (and formed earlier).
As we toured the mines I learnt that rippled sandstone is usually hard and dense with an unusual thickness, sometimes as much as 8 or 9 inches. It’s heavier than other layers of sandstone and can be quite brittle, like glass. It even rings like glass when you strike it.
These properties make it liable to break in unpredictable ways when you take a chisel to it and this could be one reason why mine owners deal with it almost like it is 'mine spoils’, fragile and nearly useless except when it has been reduced to small, linear tukdees.
GOLAK KHANDUAL:
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I wondered if we’d be able to find even a few really LARGE rippled slabs that we could cart away in carefully marked up sections that we could then reassemble on site.
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Persistence paid off!
On our third or fourth day of roaming through Soorsagar’s mines, we felt we had been divinely guided to the open yard of an aficionado mine-owner who had an unusual shauq – he had somehow put together an assemblage of really big slabs of lahariya bhaakad, each one unique and stunningly beautiful.
Exactly what we had been looking for!
The only trouble was that he knew how uncommon they are in large dimensions. And he wanted his price. Eventually, after an unseemly amount of haggling and beseeching, we managed to acquire some seriously large rippled slabs, a few of them stretching to 10 feet long.
Now we needed to figure out how to cart them to our Visitors Centre site.
At some point during the operation I changed my mind about cutting them up into smaller pieces even though I knew that shifting them around once they reached the Visitors Centre was going to be really difficult.
I made tiny cardboard models to scale of each of these big slabs and numbered them. Playing around with their shapes and odd sizes, I tried fitting them optimally into the width of the pathway.
This worked!
When the cranes had lowered all of the huge slabs at designated places with an economy of movements, our brilliant Khandwalias did the fine tuning and cleverly nudged them into place with their crowbars.
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I decided not to use any cement concrete for a sub-base. Preparing the ground involved a bit of ramming and levelling with just sand and stone-dust. The self-load of these slabs was so immense that once they were placed on level ground nothing could budge them by even a millimetre.
We left wide joints between the edges of the slabs, partly because it would have been difficult to achieve good fits but also because we didn’t want to create an impervious surface.
Then we filled the spaced-apart joints with a contrasting dark purple rhyolite moongia, which is what crushed stone (grit) is called in Jodhpur. The decision not to have an impervious sub-base as well as keeping the joints open was all about helping rainwater to soak into the thin garden soil.
The plants were going to need all the help they could get.
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As finishing touch to the ripplestone walkway, we needed to cover the rainwater drain that ran across the front of the Pol.
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Except for this one!
We tell visitors these pugmarks were made by a particularly heavy dog...
(I wonder why no one gets fooled!)
All these cutout motifs were drawn from patterns Golak found somewhere or the other inside the great Fort.