Strange rock - crannog

Muineach

hya,
I been meaning to ask someone about this for years, so here goes.
In the picture below are the "divit" in the rock natural or man made ?
I know the rock was used as a block, it's the divit that I'm interested in.
There are quite a few around what was once the Lagore Crannog, which was an Irish royal residence of the seventh to tenth centuries.
I would have asked a geology group but there doesn't seem to be any.

I always presumed that they were natural, mabye I'm wrong ?
if they are natural any ideas on how they formed ?

Thanks
Muineach

boneless

Bloody good question!! I am inclined to think they are natural. It could be due to water erosion. I am sure though, that someone here will have the answer.

Hey Grimes... ask Aidan O'Sullivan. I think he worked on Lagore...

Fletch123

They look absolutely natural to me (water erosion). I've seen them in different parts of the country, usually in areas of soft rock.

The block may have been exposed to the elements when it was deposited there (from a derelict building etc).

However, the block may have been selected for the attractive pattern that it has.

Is there anything else nearby? Are the blocks you saw at Lagore in the vicinity or actually on the Crannog? Anything else nearby that might give it a context?

Riamfada

Id say its water erosion of some type. They look to deep and smooth to be any type of picking .

If i see Aiden ill ask him

Muineach

Some more info:

Where I found the stone was a man made ditch, well all of the ditches here seem to have been deepened by man, down to about 5-7 foot and stones were then built into the wall to hold back the soil. Outside my house there's a 4 foot wall built into the ditch with it being 2 foot below the topsoil. My parents bought the site back in the early 70's and it was there when they moved in, before that it was just a field.

here's a better view of the local area, thanks to yahoo maps
They took the photo's last summer during a dry period so you can see the difference in the drainage as well.
http://maps.yahoo.com/#lon=-6.514887&lat=53.514861&mag=1

From my reading of the crannog it seems that it was located just NE of the center cross (yahoo), but from the aerial photo to me it seems that it might be to the west, they are 2 semi parallel lines that seem to be coming into a circle at either end.

The line running through them was a ditch to drain the "lake/bog", I have a picture below, its about 8 foot wide.


From looking at the maps I found another spot about 500 meters to the east, where it looks like 6 "walkways" all center on one central point ?
http://maps.yahoo.com/#mvt=h&q1=dunshaughlin%2C%20meath%2C%20ireland&trf=0&lon=-6.505199&lat=53.515193&mag=1

C Fodder

This is natural erosion. The rock was taken from the edge of a lake at some stage. You will see this type of erosion where there is exposed limestone by the waters edge.

Hot Dog

I think its a karst type texture, or less likely borings by bivalves or the like. Yes

delos

Hot Dog wrote: »

I think its a karst type texture

Indeed it is . If you go up to the shores of Lough Mask and Lough Corrib you'll see lots of this type of weathering