Images from the estuary foreshore

I don't get how those trees, which seem to be fresh water species, can live to close to the banks of seemingly high, (by the looks of the various shellfish), salt water intrusion inlet. I guess what streams you do have in that valley are sufficient to hold back the salts. Interesting ecosystem.

Gary
 
Gary said:
I don't get how those trees, which seem to be fresh water species, can live to close to the banks of seemingly high, (by the looks of the various shellfish), salt water intrusion inlet. I guess what streams you do have in that valley are sufficient to hold back the salts. Interesting ecosystem.

Gary
Click to expand...

Hi Gary,

The trees you see are indeed species such as Oak. Having been born and raised in the locality I accept the ecosystem as quite normal and have never given much thought to the point you raise.

Technically such a feature is known as a "ria" and is actually a valley that has been drowned by sea level rise at some time in our geological past. They are a feature of the south west peninsula of the UK and also occur in south west Ireland and north west Spain.

Unlike the low lying land of a salt marsh where the land is flooded by salty water at high tide and only salt tolerant plants can grow, the banks of these inlets tend to be steep sided and the hinterland is usually a steep slope down from the surrounding hill. Also the underlying rock is usually close to the surface and in the main forms the banks where it is often exposed. I therefore imagine that salt ingress is no problem and doesn't really occur.

Whilst many rias have river systems flowing into them the particular one photographed only has small streams inputting any fresh water. So whilst it is called the Kingsbridge Estuary it is not technically an estuary, an estuary being defined as the mouth of a river where tidal effects are evident. There might be some influence by the fresh water input and thinking about those that I am familiar with it's probably true to say that the trees come down closer to the water (in a vertical sense) the further away from the sea entrance that you are. However it might be that the rock tends to be more exposed nearer the mouth of the ria probably due to more wave action. Being relatively sheltered there is little or no airborne salt such as can occur in stormy conditions on exposed coastlines which can influence the plants capable of growing there. The lowest branches of the trees tend to mark the water level at the highest spring tides, so forming an almost straight line as you would get in a wooded area grazed by deer.

So endeth my diatribe on geography matters :)

Barrie
 
Okay ... I'll sorta buy that as a Ria is formed from glacial action, I can see the combination of ice gouging and water erosion going down to a rocky, somewhat impermeable strata ... it is just so odd to see Oaks, (which is what they seem to me), which I believe are acutely sensitive to salts, that close to a brackish water source. Maybe they evolved to a more tolerant variety ... combined with the rocky containment of the brackish water ... it works. Anyway, thanks for the discussion.

Gary

PS- You mentioned you were moving, have you made the move?
G
 
Gary,

No glacial action in the formation of a ria, our area was south of the last ice age. A ria is a V shaped valley, so the initial valley is formed by action of water, not ice. The woods are indeed mostly of Oaks.

Barrie

PS, no move as yet, am still waiting for contracts to be agreed between my buyer and myself, so it could still go wrong!
 
grebeman said:
Gary,

No glacial action in the formation of a ria, our area was south of the last ice age.
Click to expand...

That's a bit hard to take. South Wales here is well rounded As is most of Devon & Cornwall. I also recall seeing a programme about Ice age people migrating from Bordeaux area of France to America following the ice coast.
 
I stand corrected - amazing you are what 80 miles away due south from me & it was warmer?
I've been busting my brain trying to remember the name given to the type of stone axe they found in East coast America - if I find it I'll post it
 
grebeman said:
It wouldn't have been much warmer, but just enough. I remember seeing tadpoles in glacier melt water at 16,000 feet up in the Andes, just about 300 yards from where the glacier terminated, so not much warmer for them, but just enough.

Barrie
Click to expand...

Yep, just enough has to start somewhere ... in this case the southwest. Actually, I am surprised, like ReD I would have assumed all of the UK to have been iced. The adaptions of organisms living on those 'just enough' edges of the world are fascinating, worthy of a book. (hint)

G
 
Back
Top