Who's Fault Is It?

In our final year of B.Sc., we had been to Bhuj in the state of Gujarat for our annual field trip. We were supposed to be heading for Malvan in the southern part of Maharashtra. But some crazy circumstances forced us to head north into the dry region (most of us know what I mean by dry region :p) of Kutch. It was unexplored and uncharted territory. Our professors were relying on past experiences and reference materials. It very often happened that we would stumble upon something completely new and start breaking our heads over the mystery of the outcrop. It was during one of these exploratory trips that our professor realized that there was something weird across the road that ran in front of our lodging.

So, one fine morning (half asleep actually), we walked up this small hillock. Once we were at the top, our professor pointed out this feature to us.

Naturally, we were confused. We did notice that long linear mark on the surface. But we had no idea what it could possible be. Lots of options ran through our minds. A dike maybe? Or was it a fault? It could also be some thin rock strata of a different composition. With these thoughts, we started our investigation.

We began with the thin zone marked in red in the pic above. The material within that was definitely fine grained. Extremely fine, to the point that it felt like it was crushed. It was highly jointed, with sets of joints running perpendicular to the length of the zone as well parallel to it. As expected, there was intense venation around it.

We cast our attention to the surrounding area. We noticed a reddish ferruginous sandstone bed on one side. But,no matter where we searched we couldn't find the corresponding outcrop on the other side. This eliminated a lot of our guesses and we had narrowed it down to one option. It was definitely a fault. But we needed proof. And that we got.

Small striations (or as we know them: slickensides) were noticed by someone on the rocks on the supposedly upthrown block. And as a bonus, we got some minor faults at the top of the hill. So, that was it then. Mystery solved.

It was our fault. :P

P.S. The road is called the Bhuj Airport Road and the fault is located right opposite to Navchetna Lodge. So, if you ever feel like, you can surely go. Maybe you'll find a pencil or something which one of us left behind.