Thread- Wonders of the Deccan Landscape. A 66 million year river of lava...exhumed!
On Pune Nasik Road, turn east at Ale phata. Look for Mandohol Dam. And a ridge named Mhasoba Zap.
Can you spot the lava river?
On Pune Nasik Road, turn east at Ale phata. Look for Mandohol Dam. And a ridge named Mhasoba Zap.
Can you spot the lava river?
Basalt lava is less viscous and can flow for long distances. It can get channeled along a preexisting valley or follow lows in the landscape, forming a sinuous lava channel. Pic from USGS captures a lava channel from recent eruption in Hawaii.
The view in this pic at Mhasoba Zap is looking upslope. The sinuous ridge you see is the exhumed lava channel. It stands out as a ridge about 100 meters above the adjacent plains.
Here is the lava channel looking downslope. It continues for a distance of 4 kilometers 'downstream' before dying out.
And this is the margin of the channel. You can see the rock is reddish in color. A closer look (in the field) will tell you that it is glassy to fine grained and appears fragmented. Lava at the margins cools quickly. The iron in the quenched matrix rusts.
In close up I have outline the base of the channel in orange lines. My friend Dr. Sudha Vaddadi (ex GSI) who has mapped this channel tells me that this entire ridge is actually a lava tube. The top has been eroded away! She was able to identify the 'roof' a km away downslope.
Lava at surface cools & solidifies quickly. That leaves a tube or a pipe through which lava is supplied from vent across long distances. The solid crust insulates & keeps interior hot allowing long flow distances. Pic is a lava tube from Reunion Island. Pic Credit. Nandita Wagle
A closer look at the margins. You can see the reddish color and the fractured fragmented nature of the rock. Cracks are filled with secondary minerals (white veins) of scolecite (zeolite) and calcite.
Blobs and lava spatter accumulates at the margins, cooling and welding together to form an 'agglomerate'. You can see globular masses stuck together.
Stepping back and looking at the lava channel. You can see a distinct sinuous shape. Downslope it breaks up into distributary 'fingers'.
Although the Western Ghat escarpment with its spectacular views captures a lot of attention, the Deccan plateau region to the east of #Pune also has a host of interesting features.
Get out there and explore!
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Get out there and explore!
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