Gilbert Hill is on shaky ground
MUMBAI: Situated close to Bhavan's college in Andheri (west), Gilbert Hill is a rare and unique volcanic structure that is now in the danger of collapsing because of haphazard growth of buildings around it.
On Tuesday morning, when another deluge hit Mumbai, large boulders of black basalt came crashing down from the top of the 200-foot-high hill, much to the shock and dismay of locals. Fortunately, no one was hurt as people were indoors due to the downpour.
A resident who witnessed the incident said: "There was a loud noise as boulders came crashing down during the rains. The earth shook and everybody was very scared."
Geologist and former IIT professor, V Subramanyan, who has been studying Gilbert Hill for the last five years, said the incident was a clear sign of the damage inflicted by unmitigated development all around the structure.
"The hill has been declared a national monument by the Geological Survey of India, but it is highly unstable due to the reckless encroachments."
A number of highrises have come up all around Gilbert Hill in recent years, triggering concerns for its stability. The Bombay HC had directed an IIT-Powai team to survey the hill and suggest measures for its protection.
The HC has also stayed all constructions around the hill for the past one year. The ruling may help rescue the pre-historic structure believed to have been formed due to a volcanic eruption around 65 million years ago.
"Nowhere else in the country is there a residual hill formed of columnar rock like this and it so deserves to be preserved at all cost," said Subramanyan.
Gilbert Hill has survived the extensive quarrying that has been going on all around it for years. One of the trustees of Gaondevi temple situated atop the hill, S Pardeshi, told TOI: "We have appealed to the municipality, collector and other authorities for years to save the hill from builders and other encroachers, but nothing has happened."
Excavations at the hill's base will remove the 'toe support' for the columns and destabilise the hill and in due course, the columns will open up at the top and fall off on the sides, according to Prof Subramanyan.
"The only solution would appear to be to 'grout' the joint-openings between the columns so that they do not spall off on the sides."
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ENGLISH MAN AT FOX HUNT; AT ANDHERI RAILWAY STATION 1885[WHEN ANDHERI WAS AN UNINHABITED PLACE IN BOMBAY]YOU CAN SEE ANDHERI RAILWAY STATION WHICH WAS THE ONLY BUILDING;IN THE PHOTO DOWN; AT THAT TIME THERE
ENGLISH MEN USED HUNTING DOGS; HORSES AND POOR INDIAN COOLIES AS SEEN IN THE PHOTOThis photo removed by?i think by the same people as foxhunt
ANDHERI RAILWAY STATION 1885[WHEN ANDHERI WAS AN UNINHABITED PLACE IN BOMBAY]
fox hunt in Bandra - Bombay-1850
fox hunt in madras(now chennai) 1910
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fox hunt in madras(now chennai) 1910
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-------..................................................---------.............................--------------------........................................Excerpted from Once Upon A Hill by Kalpish Ratna
I drive down a crooked lane that bisects a pullulating shanty, turn left, and find myself confronted by the rocky stub of the south end of the hill. The rocks here are variegate with sedimentary stripes of human faeces encrusted into vertical stratifications that speak of an entirely different set of geological hazards.
But, what’s this?
Beneath the litter the rock shows true stratification—horizontal stratification. Breccia and tuff make up the sponge between the lava layer. I think this is what surrounded the columnar basalts.
I gather my notes and try to make sense of what I’ve seen of the invisible parts of Gilbert Hill. The columns of basalt are topped by rock that has horizontal stratification. But this I can spot only at the southern end of the monolith. The rest of the top is covered with a thin layer of murram—laterite, deep enough to support shrubs and small trees.
So what did the top of Gilbert Hill look like, before it was quarried?
Densely jungled, according to Norshirwan, the son of the man who quarried Gilbert Hill. Norshirwan’s uncle, who died recently, was the memory-keeper of this place, having been around since the first assault on the hill.
That was in the mid-1930s, when the Government invited tenders to raze the hill and develop the land.
The hill was thickly wooded then.
Was there a river? Were there streams?
Nobody knows.
There are no photographs.
Nobody lived on the hill.
According to Noshirwan’s uncle, there was no temple up there. His story of how the temple came about is a little more believable than Guruji’s Vijayanagara myth. When the quarrying commenced, the labourers set up a little shrine to bless their endeavour. Noshirwan’s uncle, the overseer, already had a masjid on his premises. Once the monolith emerged, and the labourers had to scale it every day, it seemed only politic to station their guardian at the summit. It was a neat and harmonious compromise—the Mandir on top of the monolith and the Masjid at the foot of it. Everybody, and the enterprise, was doubly blessed.
Norshirwan’s story is an interesting diversion, but he still didn’t have enough for me about the invisible hill. What he did tell me was this: the southern stub of the hill, that chunk of stratified rock I’d seen outside Sagar City, had been uncovered just six years ago. Till then that area had been occupied by a gigantic heap of murram from the blasting. When that was cleared away, the hard rock beneath was revealed.
But there was more to Gilbert Hill than the monolith. What made up the rest of the hill?
At the northern end of the monolith I had seen a wide convexity of wrinkled stone, like the back of an elephant submerged in a bog. Pillow lava? That would mean an eruption of lava under water. The dome has crenellated markings, like the advancing toes of a pãhoehoe. At one point a cleavage line shows the underlying layer fitting matrushka-like into the convexity. At other places, the rock has a dimpled, almost cushiony, appearance, though the surface is ridged too sharply for comfort.
The east end of the cutting near Sagar City shows the columnar formation placed above a stratified base. Further south, the stump of the hill stops at the stratified layer, in which ash—finely granular, close-packed, biege to brown in colour—alternates with thin glassy plates of basalt.
Not all the perimeter of the stump is brown. Buffalo-grey basalt
soon takes over. Here, the emplacements have amygdaloid bodies—most are embedded in the rock. Some layers are pockmarked. They must have contained amygdules that have been shed.
I recall the pillow lava
at the base of the monolith. The white patches are changes in the rock—it has become albitic. Technically, this metamorphosed basalt is a spilite.
Such a change is brought about by contact with seawater. This volcanic eruption was submarine.
Map showing distribution of Deccan lavas and associated intrusives in the Western and Central India
"Deccan Volcanic Province" (DVP):-
DVP is exposed mainly in the states of Maharashtra, Madhya Pradesh, Karnataka, Gujarat, and Andhra Pradesh .Today, the DVP occupies an area of over 5,00,000 sq. km however, original estimates of the extent of the lava pile prior to erosion and possible down-throw on the western side into the Arabian Sea are of the order of 1 to 1.5 million sq km. The lava pile has a maximum thickness of over 1.5 km in the western parts of India.
“Mad or wot?” is Cajetan’s comment when I tell him about the pillow lavas. “I don’t think the sea was coming upto there, right upto the hill, not even in my grandfather’s time. Or people would have noticed, no? Reason nobody noticed Gilbert Hill was because it was a normal hill.”
Lava toes exposed in Girna River bed in Nasik district, Maharashtra
I don’t want to challenge him over the definition of a normal hill.
“It wasn’t this sea,” I explain. “It was the Indian Ocean.”
He looks concerned. He calls for iced water. He offers me a seat closer to the fan. He hollers for tea.
He nods intelligently as I tell him that 65 million years ago, during the K-T extinction, India, recently ripped off from the Seychelles, was a little south of the equator, and on its way to a collision with the southern margin of Asia.
His daughter Letty-for-Letisha brings tea and biscuits and stays on to listen.
“Letty, go finish your homework,” instructs Cajetan curtly.
“I finished.”
“Go, go!”
Letty goes.
“Can’t have her geography spoilt,” Cajetan tells me. “India is above the equator, even I know that.”
“It is. Now. But not 65 million years ago. Then, it was moving upward.”
“Yeah. Sure, sure. Tell you what—forget Gilbert Hill. You want to see other places? Sure, we’ll go. But not Gilbert Hill.”
“Okay.”
I have stretched my credibility too far with Continental Drift. He must be relieved of Gilbert Hill.
“This hill now,” Cajetan suggests carefully, “you could start with this one.
Go little bit north and it’s Vyaravli.”
“Yeravli, you mean?”
“Vyaravli—Yeravli, some people say like this, some like that. Little bit further up is the lake. Vyahr Lake.”
Vihar Lake.
I hadn’t realised till I heard Cajetan said it thus, that Yeravli might actually be Vyravli.
Yeravli is very close to the hill on which I live—Malpa Dongar. Before they blasted Malpa to build homes for one lakh people, the hill probably stood shoulder to shoulder with Yeravli. The highway cut through both of them. The two were probably one hill. The Kondivti caves of Mahakali Road
are in Yeravli. Perhaps the division between them was artificial.
“Tell you what,” Cajetan says kindly, “why don’t you look at all the hills? Maybe they’re all like Glbert Hill.”
Are they? I need another map to answer that.
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Excerpted from Once Upon A Hill by Kalpish Ratna, HarperCollins India. The book is due for release this month
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[2] Devils Postpile National Monument is located near Mammoth Mountain in extreme northeastern Madera County in eastern California.
[3]
