Hi Rhiannon ,There are certainly some very RA like features found on coastal rocks but what gets called crotagan (various spellings) or bait holes are usually man made . As Goffik suggests , just becausee they were used for that purpose in the past doesn't mean that was the original reason .

You're right to question these marks Rhiannon.
There is some debate to the origins of these Scottish seashore carvings - not these particular ones but shoreside ones in general.
They are often thought to be 'bait mortars' or 'crotagan' - small cups used when grinding bait for fishing and there is definitely some evidence that points to them being used for this purpose.
See Graeme C quoting Morris on the subject
http://www.alkelda.f9.co.uk/lore4.htm

Of course this doesn't mean that all such cup-like depressions are bait mortars. Margaret Cutis recently showed me a whole heap of these carvings close to Bernera Bridge on Lewis, which she discovered whilst out canoeing with Ron G. The carved rocks were covered in multiple cups of varying depths and were within the tidal zone and sloping towards the sea.
It struck me that the idea of these being bait mortars didn't really fit-in with their frequency, morphology and distribution along a number of sloping rocks.
Margaret had showed them to Ronald Morris but he dismissed them as mortars because of their location within the tidal zone. What Morris didn't take into account was that in prehistory the sea level was approximately 5m below the present level and the loch would have been a river.

The cups aside, Margaret had me in stitches as she crossed a half submerged seaweed covered causeway and then leapt about the trecherous rocky weed covered shore in two left wellington boots.
I don't really go in for heroes but if I did she would be mine.

There is always the possibility that the smaller ones are natural and the larger ones are enhanced. Many bullauns are by water, so I have no problems with seeing these ones next to water.

I have no doubt that some bullauns were actually formed in river beds by tumbling rocks and moved to the shore for use. There are still places where 'bullauns' in river beds are thought to be some saint's knee-marks made when he baptised the local king.

Hi all

Some really good points being raised here!

After my visit here, I'm quite convinced that these are something other than natural markings. Partly, as mentioned before, because these rocks are the ONLY ones in the area of (I'm no geologist, but) exactly the same rock-type. And partly because they look exactly like all the other countless cupmarks I've ever seen! (Although, again - I'm no expert!)

I suspect that most doubts regarding the shape/distribution could be largely due to the erosion. Remember though - this is RIGHT on the edge of a really exposed bit of land in the far west of the Hebrides. And we know what the wind/rain/waves can be like in that neck of the woods!

I've posted a couple more pics from my phone which may help clarify or confound...

http://www.themodernantiquarian.com/post/47296 and
http://www.themodernantiquarian.com/post/47295

G x