Remotely India Series #12 Through the Proterozoic Eon, beginning around 2 billion years ago,  extensional forces acting on continental crust opened up several sedimentary basins across what is now peninsular India. Crustal blocks subsided along faults and these depressions filled in with sediments deposited in fluvial and shallow marine environments. These basins were long lived, some lasting for more than a billion years.  Sedimentation was not continuous.  Pulses of sediment deposition were punctuated by long periods of non deposition. Tectonic movements deformed early d ..read more

Reading from the past few weeks-  1) How earthquake scientists solved the mystery of the last “Big One” in the Pacific Northwest. The American northwest is a tectonically active region. About 150 km west of the Pacific coast is the Cascadia subduction zone. Here, the Juan de Fuca, Explorer, and Gorda tectonic plates slide underneath the continental plate of North America. Large earthquakes have occurred in the past and will occur in the future.  Reporter Gregor Craige has written a book, On Borrowed Time: North America’s Next Big Quake, in which he explores the region's earthquake po ..read more

Charles Darwin famously called it an 'ábominable mystery'. He was referring to the sudden appearance and diversification of flowering plants in the Cretaceous fossil record. He noticed that these early fossils resembled modern flowering plants. 'Primitive' or ancestral stages were missing. Today, biologists categorize these as crown and stem representatives of a group.  The first fossil evidence of flowering plants is from 140-130 million year old sediments. These are early types of pollen grains with one aperture (uniaperturate). Triaperturate pollen is found in slightly younger 125 mill ..read more

My latest field geology video is about a small cave in the basalt lava near my house in Pune city. The location is Hanuman tekdi, also known as Fergusson College Hill. The cave is along the slope right behind IMDR canteen.  Is the cave a remnant of a lava tube, or has it formed by some other process?  Sound on. Permanent Link - Fergusson College Hill Cave. You can access this cave by walking along the path starting from the main gate of Gokhale Institute of Politics and Economics. Turn left as you approach the hill and after a few steps look up to the right.  Visit quickly. As ..read more

This passage from Helen Czerski's Blue Machine: How The Ocean Shapes Our World gives us a glimpse of the wondrous undersea universe we are just beginning to explore. "We see upside-down waterfalls, she says. I don't understand what she means at first, and it takes me a few seconds to process the video as Deb keep talking. In those vertical chimneys, the walls crack and hydrothermal fluids come leaking out and  you get something that looks like half a toadstool growing out of a tree in an old growth forest. And suddenly I see it. This is a gigantic hydrothermal chimney looming out of the d ..read more

I have been experimenting with shooting videos of geological features with an accompanying commentary. Here are two of my recent efforts. Last month I visited Kenjalgad, a small fort near the town of Bhor. As is typical of forts of the Sahaydri ranges, it sits atop a thick basalt scarp.  The videos explain the geological conditions for the formation of a perched aquifer. I hope I have been clear in my explanation. Sound on please!  Kenjalgad aquifer. Location 1- Permanent Link Kenjalgal aquifer. Location 2- Permanent Link Kenjalgad as seen in this picture is quite an impressive me ..read more

One of  my favorite courses during graduate work in Pune was geological Remote Sensing. We focused a lot on visual interpretation of aerial photographs and satellite imagery. Lab work meant hours of poring over different areas of India and making preliminary geology maps based on observations of the landforms and rock structures visible from space. The rock composition, structure, and weathering patterns controls the surface expression of geological units. These are manifest on satellite imagery and on aerial photographs as differences in tone, texture, structural styles, and relief.  ..read more

A couple of weeks ago Iceland awaited with much anxiety as magma made its way to the surface. A volcanic eruption seemed imminent. That danger seems to have passed for now. Seismicity has abated and magma may not break through and erupt. Misunderstandings regarding climate change though shows no signs of receding as this comment shows -   Source: X - https://twitter.com/dremtee/status/1723427183182446871 Ever so often it is worth putting up the numbers: Anthropogenic CO2 emissions - About 40-50  billion tons per year. Volcanic CO2 emissions - Approximately 500 million tons per ..read more

 So near Pune, yet I had never been to this location near Bhor. It is popularly known as necklace point. The river Nira loops its way through the countryside forming a series of lovely meanders. A high point overlooking the valley allows a clear view of this feature.  I was on a drive with some friends, spending the day exploring the back waters of the Bhatgar and Nira Deogarh dams. We eventually reached Warandha Ghat, one of the spectacular passes linking the Deccan Plateau with the western coastal plain.  At the edge of the plateau, high relief exposes sheer rock faces.  ..read more

I came across this stunning image of a mineral filled vesicle on the September 2023 cover of Geology. The rock sample was collected from the Louisville Seamount Chain in SW Pacific Ocean.  Source: Elmar Albers et.al. 2023- Timing of carbon uptake by oceanic crust determined by rock reactivity. Vesicles in igneous rocks are spherical holes formed by expanding gas bubbles. As lava erupts, dissolved gases bubble out. Lava solidifies fairly rapidly on exposure either to air or water. The bubble shape is retained as a small cavity. It gets filled with minerals when magmatic fluids and mineral ..read more