In article ,
(Nick Maclaren) writes:
|
| According to all the references I have seen (in particular Yalden
| and Birks), the glaciers still reached down to the Midlands in 11,00 BP,
| and the ice-free parts of Britain were tundra. If that date is wrong,
| make it 11,500 or 12,000 or whatever matches.

Upon checking, the coldest period of the Younger Dryas was 10,200 BP,
and that is the latest date at which the whole of the UK would have
been effectively tundra. The glaciation was not major during that,
because it was fairly short.

Even for those relics of the Windermere interstadial survived the
relatively short cold spell of the Younger Dryas, the extended cold
spell which culminated in the Older Dryas and had the properties to
which I referred ended only in 13,000 BP. The glaciation peak was
20,000 BP.

Virtually ALL of Britain's multi-cellular organisms have arrived
since then, and the ecology has never been stable (or 'natural')
since.


Regards,
Nick Maclaren.

In article ,
Malcolm writes:
|
| Virtually ALL of Britain's multi-cellular organisms have arrived
| since then,
|
| Obviously since 20,000 bp and most since 13,000 bp. That's fine, you've
| shoved your original 11,000 bp back enough in my view.

Yes. I had simply forgotten the relevant date.


Regards,
Nick Maclaren.

In message , Nick Maclaren
writes

In article ,
Malcolm writes:
|
| There are only a few multicellular plants or animals that were here
| 11,000 years ago that are still here today.
|
| How do you work that out? 11,000 years ago, i.e. 9,000 BC, Britain had
| tundra, forests, marshes, freshwater lakes, rivers, streams, etc., all
| holding a huge range of plants and animals, the great majority of which
| are still here today, including man.

According to all the references I have seen (in particular Yalden
and Birks), the glaciers still reached down to the Midlands in 11,00 BP,
and the ice-free parts of Britain were tundra. If that date is wrong,
make it 11,500 or 12,000 or whatever matches.

It is unlikely that any species of tree grew in the UK then, except
perhaps for Scots pine and JUST possibly birch, or more than 2-3
species of mammal (probably not including man) that are here today,
according to Yalden. There were many more in the warm periods, of
course.

Invertebrates are harder to estimate, but there is some evidence for
beetles.


Regards,
Nick Maclaren.

You wrote "only a few multicellular plants or animals that were here
11,000 years ago that are still here today". While it is clearly true
that most of the species that are here today weren't present then, it is
not so clearly true that the majority, or even most, of those that were
present then have been lost - rather they have retreated to the
Cairngorm Plateau, the crags of Ben Lawers, the moss carpets of Ben Hope
and Ben Wyvis, the outcrops of the Durness Limestone, etc., and perhaps
even the Burren and the limestone pavements of the Pennines, and the
cliffs of Snowdonia, etc.
--
Stewart Robert Hinsley

In article ,
Stewart Robert Hinsley writes:
|
| You wrote "only a few multicellular plants or animals that were here
| 11,000 years ago that are still here today". While it is clearly true
| that most of the species that are here today weren't present then, it is
| not so clearly true that the majority, or even most, of those that were
| present then have been lost - rather they have retreated to the
| Cairngorm Plateau, the crags of Ben Lawers, the moss carpets of Ben Hope
| and Ben Wyvis, the outcrops of the Durness Limestone, etc., and perhaps
| even the Burren and the limestone pavements of the Pennines, and the
| cliffs of Snowdonia, etc.

A fair point. In addition to getting the date wrong, it was badly
phrased!


Regards,
Nick Maclaren.