From Patton et al, 2013, modified. The three big outlet glaciers draining westwards from the Welsh Ice cap were the Tremadog, Mawddach and Dyfi Glaciers. Separating them are the three sarns ++ long ridges of morainic debris exposed only at low tides. They have much mythology attached ++ relating to Cantreär Gwaelod or the lost Lowland Hundred. See other posts on this blog. The confluence or contact between Welsh Ice and Irish Sea Ice shown on this map must have moved eastards and westwards as the relative strengths of the two ice streams changed over time within and between glaciations. The survival of the sarns shows that the last significant glacial episode to affect this area must have involved an expansion of the Welsh outlet glaciers. They would not have survived an assault by Irish Sea Ice flowingv from the N and NW.
Rapid marine deglaciation : Asynchronous retreat dynamics between the Irish Sea Ice Stream and terrestrial outlet glaciers
December 2013
Earth Surface Dynamics 1(1)
DOI: 10.5194/esurf-1-53-2013
H. Patton et al
Outlet Glacier flowlines and surface velocities, after Patton et al.
The view from high above Pwllheli, as it might have been.....
6 comments:
I recently spent some time on the Llyn peninsular, and I noticed quite a selection of boulders just beyond Aberdaron, one of which was a large green sandstone erratic. Very interesting.
ORS? Could be interesting...... do you have a grid ref or any photos?
The boulder is in Porth Meudwy bay. I have photos if you want them.
Yes please! You could send them as jpegs to me at brianjohn4"at"mac.com. Will be very interested to see them.......
I've sent them to you, Brian.
Thanks Andrew yes, I received them and have been mulling over what they might be made of! Been getting some advice from a colleague. Will do a post soon........
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