A Menhir or an Insitu Rock or Natural Rock, an analysis with Experts and Geologist, Chinnathambipalayam, Namakkal District, Tamil Nadu.

After completing my session on the “Prehistoric places in Kongu Region”, organized by Tamil wiki – Thooran Viruthu Vizha 2025, on 16^th August 2025 at Kavundachipalayam between Erode and Chennimalai, Mr. Krishnan told me about this menhir and the article written by Mr. Jayamohan. In the article, Mr. Jayamohan mentioned that this menhir, and pointed out that the same was not documented in our blog. So decided to visit this menhir along with Mrs. Sakthi Prakash, co-author of my blog, at Chinnathambipalayam, near Tiruchengode, and Mr. Krishnan also arranged a vehicle. This Menhir is on the bus route from Tiruchengode to Salem, about 5 km from Tiruchengode.

The flat rock is about 8 feet wide and 15 feet high, and its thickness is about a foot. Cracks are also observed on the surface. Mud pots are found on the base of the flat rock. It was said that the locals worship this rock is considered Kattu Karuppasamy. A similar structure of rocks is found on the edge of the field and in some more spots in the surrounding villages.

We had a doubt that this standing flat rock may not be a Menhir; instead, it must be a natural rock. Similar rocks are standing at the edge of the field, but they are shorter. Also, we couldn’t find any evidence to prove it as a Menhir. Certain criteria are missing. Ancient red and black pot shards around this place, cairn circles in this area, or nearby Villages, water sources like ponds / eri, etc, are missing. So this is not a menhir, and this is a natural formation of rock.

In this connection, we thought of getting an opinion from a Geologist to support our conclusion. The expert’s opinion is also given below.

    

THE OPINION OF Mr. SHRIDHAR GANAPATHY, GEOLOGIST.

Veludharan Sir,

Happy to interact with you.  

You had raised a query, whether the rocks shown in the picture sent by you are Menhirs or in situ rocks?.

You also informed during the discussion that Rocks used for Menhir monuments could be stones that are brought from a distant place 

 or

In certain cases, if rocks are available in close vicinity, a Menhir is constructed using the same rock material.

OBSERVATION

From the pictures supplied, we could make two sets of rocks. One is called mother rock, or the earlier-formed rock. (In the schematic drawing, shown in Blue color and in the picture with a soil layer probably having less nutrients, where plantations like ground nuts are grown, indicative of less availability of water.

The original country rock type is non-identifiable as the rock is highly weathered to form a soil layer.

The second type of rock, as seen in the picture, is known as Migmatites. This is relatively a later formation compared to the country rock. This can be identified as wavy-like (striated rock), which comes under the broad classification of metamorphic rocks. The rock has quartz, Feldspar, and Biotite (black in color and flaky in nature). In the schematic drawing, it's Red in color.

Inference

Having explained the rock feature as seen in the picture, one could conclude the Migmatite as a metamorphic intrusive. To put it in a simpler way, Migmatites, in Fluid or semi-fluid form, were injected into the already solidified earlier country rock through a weaker plane. This is seen clearly in the field with a certain linear orientation.

The country rock is seen as a soil formation, as it is an older formation. Hence more prone to weathering. This rock, probably may also be relatively soft, hence more subject to weathering, giving rise to soil formation. It is difficult to make out what type of rock, before it changed to soil form, from the picture.

The younger rock (Migmatite), which was in a Fluid form, got injected into the solid country rock. Over a period of time, this migmatite solidified. 

Since it is a younger formation and also probably more resistant to weathering, it stands out, whereas the country rock has weathered, giving rise to soil formation, and hence is used for farming.

Conclusion:

Migmatites, protruding rocks which have a particular orientation, show varying degrees of weathering, whereas the country rock, being an older formation, is probably more resistant and stands out. Differential weathering shows as individual tabular structures and, in certain areas, well-formed, identifiable rocks.

Hence, what we see is a natural rock formation and not a Menhir.*

Of course, taking advantage of the raised rock formation of Migmatites, our ancestors could have built a Menhir, which I feel a trained Archaeologist could say with additional field evidence (if available)

Veludharan Sir, please call me if you need clarification.

Regards

Shridhar Ganapathy

GEOLOGIST.

Migmatite rock exposure. Migmatite shows prominent black streaks of Biotite minerals. Pink and white minerals in the migmatite rock could be Feldspar and quartz. This rock bed shows less weathering. Pl notice the rock bed, which shows a prominent orientation, indicated by an arrow mark.

Migmatite intrusive rock stands as a resistant wall. The adjoining field represents the older country rock. See the orientation of rocks and Biotite streaks indicated by the arrow

Resistant Migmatite intrusive (metamorphic rock) as a wall, along with weathered country rock soil, represents the vegetation. See a marked orientation of the Migmatites

Long shot, gives the orientation of the migmatite intrusive. Pl enlarge the picture to visualize the migmatite orientation.

Weathered Migmatites, giving rise to individual slabs and boulders.

Schematic sketch to explain the geological process that gave rise to Migmatites (which are seen in the field as beds, slabs, and isolated boulders).

LOCATION OF THE SITE: CLICK HERE

--- OM SHIVAYA NAMA ---