Sanctuary Asia - April 2018

Biodiversity within the crater was an indication of a healthy, teeming forest. The authors sighted over 120 species of birds in and around the crater,

including Ruddy Shelducks (left) foraging in the Lonar Lake. A leopard’s pugmark (right) sighted in the forest along the rim of the crater.

GAURAV SHIRODKAR GAURAV SHIRODKAR

Here, we are going to talk about a lesser known, but

equally special impact crater that formed very recently in

terms of the geological time scale. About 40,000 to 52,000

years ago, in what is today a small town in Buldhana district,

in the state of Maharashtra, a massive meteor weighing more

than a million tonne struck the Earth with hypervelocity,

creating a one of a kind impact crater, 1.8 km. wide and

more than 150 m. deep. What must it have been like at that

moment of massive collision when tremendous shock waves

ran through the Earth’s crust, sending debris fl ying all around,

before it cooled down?

For years, experts debated the origin of this crater that

formed in the basalt rock of the Deccan Plateau for it was

considered to be of volcanic origin, or a geobleme if you will,

which means formed of terrestrial processes. In the latter

half of the 20th century, further studies and observation

revealed its likeness to an extraterrestrial impact crater

and experts realised that it was an astrobleme, a crater of

an extraterrestrial source. Unmistakable signs such as the

well-shaped circular circumference, ratio of the depth to

diameter, and especially the characteristic raised rim about

20 m. above ground level on the outside of the impact

radius proved that it was indeed an impact crater. Another

important clue was the presence of fallen debris from the

impact of the meteor with the ground, around the site of

collision, making up what is called in scientifi c jargon, an

ejecta blanket. The Lonar crater’s ejecta blanket ranges over

one kilometer, including the rim of the crater. But what

ultimately proved without doubt the meterological origins

of the Lonar crater was the discovery of shatter cones,

breccia and maskelynite. Maskelynite is a type of glass that

forms when the hypervelocity impact of a meteor or asteroid

shocks the plagioclase, a rock-forming mineral, into vitrifying.

LIVING, BREATHING BIOME

This grand crater that formed when a meteor came hurtling

through space before it rammed into the Earth at this very

spot where we were now standing, is today, a thriving, living,

breathing, self-contained biome. The fact that a cosmic

hand had a role to play in the formation of this cosy, little

forested space with a near perfect circular-rimmed lake

sitting in the center of the crater, added a certain magical

aura to the place. But every image we had seen prior to our

visit failed to do justice to the actual vision before us.

The stark habitat diff erence in the land outside and within

the crater – it is as if the landscape within the crater has

been crafted and managed in vitro! The vegetation inside

the crater is a mix of dense evergreen forest at the base of

the crater, almost at the level of surface of the lake, and a

mix dry deciduous forest on the inner slope of the rim. This

forest lies in stark contrast to the dry, arid terrain outside

the crater.

The Lonar Lake’s unique characteristics have attracted

scientists and researchers from across the world. To begin

with, this is a soda lake, which means it is both alkaline

and saline at the same time. It is, therefore, a rare and

delicate ecosystem. Though, this extreme nature of the

soda lake (pH level more than 10.5) does not see fi sh

or other such aquatic life take seed here, the rare and

hardy bacteria known as extremophiles thrive in these

hostile and highly salty waters. These bacteria boast of

being descendants of Earth’s earliest living lineage which

appeared when the planet was anything but livable. They

are, today, found to be thriving in extremely hostile

conditions such as the hot and highly toxic undersea

volcanoes and sulphur vents!

But, it is not just the unusual geochemistry and biological

aspects that make Lonar special. The Lonar crater having

formed on Deccan Plateau’s basalt rock is rather similar

to the basaltic rock surfaces on the moon and terrestrial

planets such as Mars, Venus and Mercury. And that is why

scientists fi nd it to be an analogous study site for studying

these celestial objects! Lonar has been able to give us

insights into the lunar! (Pardon the wordplay).

Sanctuary | Wild Destination