<p>It's hard to tell (don't you have other photos?), but it looks like magma lenses.</p>

<p>The area is known for the Hogenakkal Carbonatite Complex, where lenses of carbonatite (a carbonate-rich magma) are found in pyroxenite dykes. See for instance <a href="https://doi.org/10.1016/0301-9268(94)90104-X" rel="nofollow noreferrer">this paper</a>:</p>

<blockquote>
  <p>The carbonatites form a series of discontinuous bodies within two nearly parallel NNE-SSW trending pyroxenite dykes intruding Precambrian chamockites. [...] Each carbonatite body consists of discrete veins and lenses emplaced in pyroxenite which has been permeated and soaked to various degrees by the carbonatites.</p>
</blockquote>

<p>But it is hard to say if this is the geological formation that you saw without more information.</p>

CC BY-SA 4.0
2019-11-04T12:47:54.460Z
2019-11-04T12:47:54.460Z
Jean-Marie Prival
<p>These photos were taken near Hoganekkal falls in south India. The darker lenses appear to be the same rock type but have varying thickness and do not form a continuous layer. How did this structure form?
<a href="https://i.sstatic.net/kgHI5.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/kgHI5.jpg" alt="rock features"></a></p>

<geology><structural-geology>
How did these dark lenticular features form? (Near Hoganekkal Falls India.)
user3377687
# How did these dark lenticular features form? (Near Hoganekkal Falls India.)

(Asked by: username_0 on 2019-10-14)

These photos were taken near Hoganekkal falls in south India. The darker lenses appear to be the same rock type but have varying thickness and do not form a continuous layer. How did this structure form?
[![rock features](https://i.sstatic.net/kgHI5.jpg)](https://i.sstatic.net/kgHI5.jpg)

**Tags:** geology, structural-geology


---

## 1 answers

### Answer by username_1 on 2019-11-04. Score: 2

It's hard to tell (don't you have other photos?), but it looks like magma lenses.

The area is known for the Hogenakkal Carbonatite Complex, where lenses of carbonatite (a carbonate-rich magma) are found in pyroxenite dykes. See for instance [this paper](https://doi.org/10.1016/0301-9268(94)90104-X):

> The carbonatites form a series of discontinuous bodies within two nearly parallel NNE-SSW trending pyroxenite dykes intruding Precambrian chamockites. [...] Each carbonatite body consists of discrete veins and lenses emplaced in pyroxenite which has been permeated and soaked to various degrees by the carbonatites.

But it is hard to say if this is the geological formation that you saw without more information.


---

