tag:blogger.com,1999:blog-1228690739485734684.post8110258176032817096..comments2024-03-28T14:00:12.372+00:00Comments on Stonehenge and the Ice Age: Lake Brynberian -- further thoughtsBRIAN JOHNhttp://www.blogger.com/profile/00413447032454568083noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-1228690739485734684.post-17194256295993142392015-05-02T18:56:04.016+01:002015-05-02T18:56:04.016+01:00Thanks Brian. Thanks Brian. Evergreennoreply@blogger.comtag:blogger.com,1999:blog-1228690739485734684.post-45067153172404500652015-05-02T18:34:16.490+01:002015-05-02T18:34:16.490+01:00.... or you can of course read "Acts of God&q....... or you can of course read "Acts of God" (available for a small fee, from Kindle) in which some of these processes are described, with rather dramatic consequences! End of plug. BRIAN JOHNhttps://www.blogger.com/profile/00413447032454568083noreply@blogger.comtag:blogger.com,1999:blog-1228690739485734684.post-87058687221215232592015-05-02T18:32:24.723+01:002015-05-02T18:32:24.723+01:00Perfectly sensible question. The extent that a sh...Perfectly sensible question. The extent that a shoreline will leave a real trace in the landscape depends on many factors. Probably the two most important are the length of time over which a water level is maintained, and the type of shore processes operating. If there are big waves and a long fetch, shore processes might be quite dramatic. If a lake is small, and frozen for a lot of the time, shore processes might be ineffective. If a shoreline is on solid rock, even a long "stillstand" of water-level might leave little trace -- but if a shoreline is on thick unconsolidated sediments (such as till or fluvioglavial gravels) a distinct notch might be cut, since even small lapping waves might be able to remove finer materials from the matrix. If sea ice or lake ice is present, all sorts of other processes come into play.... I did a big report once, with David Sugden, on high-latitide coastal processes. It's free on Researchgate, if you want a link....... fascinating subject!! BRIAN JOHNhttps://www.blogger.com/profile/00413447032454568083noreply@blogger.comtag:blogger.com,1999:blog-1228690739485734684.post-19372629008873359742015-05-02T18:16:27.571+01:002015-05-02T18:16:27.571+01:00Brian, what I know about Geology you could write o...Brian, what I know about Geology you could write on the back of a particularly small stamp, what makes something like the parallel roads of glenroy so obvious but the shoreline here more subtle? Or am I barking up the wrong tree completely with that line of enquiry? Evergreennoreply@blogger.comtag:blogger.com,1999:blog-1228690739485734684.post-35389340659945993502015-05-02T12:52:21.407+01:002015-05-02T12:52:21.407+01:00Yes, Hugh -- there is much more variation on the m...Yes, Hugh -- there is much more variation on the moorland than one thinks when viewing from a distance. I think the crags were affected by ice during the Late Devensian -- including Carn Goedog and Carn Alw. There are moulded surfaces everywhere, and I don't think they can have survived, looking quite so fresh, if they were Anglian features created 450,000 years ago. Two glaciations, one in the Anglian and the latest in the Devensian, around 20,000 years ago.BRIAN JOHNhttps://www.blogger.com/profile/00413447032454568083noreply@blogger.comtag:blogger.com,1999:blog-1228690739485734684.post-73351169797925619182015-05-02T12:19:39.951+01:002015-05-02T12:19:39.951+01:00Im so glad you have had a chance to have a look ac...Im so glad you have had a chance to have a look across Brynberian moor , I have often wondered if there was indeed once a lake here. The lie of the land is quite deceiving as it is not until you really get down into it can it really be possible to see just how it undulates then dips to the north . <br /> When you really get down into this area apart from the streams the lie of the land seems upwards in every direction . It was only after seeing this for myself I began to wonder what would have held the water back , a moraine or ice dam I wondered in my non expert head. This told me the ice HAD to have reached the outcrops on the northern slope at least once , all makes perfect sense once we actually get out there and have a look.. Is there any way of knowing which period the ice flow was intense enough to pick up and move the stones south and eastwards ? Whenever I read about it , it seems to almost always be simply described as "during the ice age"... Would be interesting to know roughly when if that was possible.. Hugh Thomasnoreply@blogger.com