MountainViews
Welcome to MountainViews
If you want to use the website often please enrol (quick and free) at top right.

General Whatever you want to say that doesn't fit under the comments about places or another forum.
Sort by >

More controls

<< Prev page 1 .. 262 263 264 265 266 267 .. 388 Next page >>
Post details Post   (Contract pics)
Mountain Views is .. by ahendroff   (Show all posts)
Following on from .. by mcrtchly   (Show all posts)
kernowclimber
2010-05-06 18:38:38
"Crinoid fossils in Dartry limestone" from kernowclimber Contract pics
Picture: Crinoid fossils in Dartry limestone (Contract pics)

Reading the rocks beneath our feet: crinoids
Simon has suggested that a description of a crinoid (mentioned in my recent Benbulben post) could be useful to other walkers who might encounter interesting fossils in the rocks while out and about in our mountains. Iím not a geologist, but mcrtchly is, so I thank him for aiding in this brief description.

Crinoids (also known as sea lilies) have been around for about 530 million years, first appearing in the fossil record of ocean sediments deposited during the Cambrian Period. These delicate creatures related to star fish, sea urchins and star dollars, resembled a flower complete with stalk and root-like parts and formed vast colonies on the floors of warm, shallow seas all over the globe during the Paleozoic Era. Some cast off their stalk and root-like anchor to become free-moving. However, many species of crinoids died out in the mass Permian extinctions, but the few that survived include the ancestors of the present day species which tend to inhabit deeper waters.

The bodies of crinoids are comprised of calcareous (calcium carbonate) plates. When these creatures die and sink to the sea floor, millions of their bodies compact over time to form thick limestone beds, some of which are eventually uplifted to form new land. As crinoid skeletons are made of calcium carbonate they fossilise easily. The stalks are the commonest parts to be fossilised and often look like stone worms when seen lengthwise and may protrude slightly from weathered rock.

Benbulben Mountain is comprised of rocks formed around 320 million years ago in the Carboniferous Period. The land that became Ireland then lay on the southern edge of a continent called Laurentia that straddled the Equator and was subject to repeated periods of inundation by the Tethys Sea. A hard and resistant rock named Dartry limestone forms the upper cliffs and precipices of Benbulben and lies atop softer shales overlying Glencar limestone.

Our fossil find (photographed) was made close to the top of the waterfall on the way up to the Benbulben plateau from Glendarragh Valley and shows fragments of crinoid stalks trapped in Dartry limestone. Benbulben is a good place to look for all sorts of fossils and near the bottom of the waterfall we found a fragment of a giant coral we believe to be Caninophyllum that thrived in the warm Equatorial waters off Laurentia.
Dessie, here's a c.. by paulocon   (Show all posts)
I found a small bl.. by kili or bust   (Show all posts)
...jackill got me .. by wicklore   (Show all posts)
Long ago and far a.. by jackill   (Show all posts)
For those of us no.. by Bleck Cra   (Show all posts)
My dear Wicklore, .. by jackill   (Show all posts)
Mcrtchly and I hav.. by kernowclimber   (Show all posts)


RECENT CONTRIBUTIONS 1 2 3 .. 18 Next page >>
Forum: General
Lough Ouler From Tonlagee
tomlug48 2 days ago.
A beautiful July day on the summit of Tonlagee. Gazing down at the beautiful heart shaped Lough Oular.Tom Barragry & the Lugs .

  
Track
Beinn Ghobhlach
Peter Walker a day ago.
Beinn Ghobhlach by evening lightWhen you're told that you can do a walk in the morning if you're quick because your o... walk, Len: 10.9km, Climb: 739m, Area: Beinn Ghobhlach, Loch Maree to Loch Broo

  
Track
Suilven
Peter Walker a day ago.
I first read about Suilven when I was about 11. It was in some British geographical gazetteer, a stern washed-out pict... walk, Len: 24.0km, Climb: 1029m, Area: Lochinver to Ullapool (Britain) Suilve

Summit Comment
Slieve Elva: Fantastic scenery
Damian120 2 days ago.
A stunning walk going up over Slieve Elva that you can begin and end end at Fanore Beach. Some great locations along the Caher River to stop and relax and watch the water gently flowing downstream...

  
Summit Comment
Knockannavea: Nice views to be had
csd 2 days ago.
While not very challenging, recent felling means the views along the way and from the summit are pleasant enough. A nice spot for a lunchtime walk.

  
Track
Maumtrasna Plateau via Dirkbeg and Buckaun Spurs
Onzy 2 days ago.
Route to the Mauntrasna plateau using the Dirkbeg spur for ascent and the Buckaun for descent. walk, Len: 10.8km, Climb: 535m, Area: Maumtrasna North-East Top, Partry/Joyce C...

Summit Summary
Knocknabro East Top: Drought made difficult ground trek possible
Collaborative entry Last edit by: CaminoPat 4 days ago.
Knocknabro East Top is best climbed as part of a good loop walk, taking in the West and North-East tops of Knocknabro. This summit is best reached firstly via Knocknabro West Top and then onto the...

  
Track
Picos de Europa
peter1 3 days ago.
I can say with certainty three things: the ascent was not 3266m, given the peak is only 2503m; secondly, I will be back walk, Len: 13.9km, Climb: 3266m, Area: Spain, Cantabria ()

  
Summit Summary
Knocknabro North-East Top: NE Top Revealed
Collaborative entry Last edit by: CaminoPat 4 days ago.
This summit is best reached via Knocknabro West Top. Park at laneway to old farmhouse now in ruin at W15905 83498. Room for 1-2 cars to park. Climb gate at entrance and follow post and wire fence ...

Track
Sail Mhor
Peter Walker 5 days ago.
After a week of blazing sunshine in the Peak District overwhelmingly spent swimming in the pool, lazing by the pool a... walk, Len: 11.3km, Climb: 833m, Area: Sail Mhor, Loch Maree to Loch Broom (Bri

  
Summit Comment
Knocknabro West Top: A Long Hard Slog
CaminoPat 4 days ago.
Park at laneway to old farmhouse now in ruin at W15905 83498. Room for 1-2 cars to park. Climb gate at entrance and follow post and wire fence heading north until W16029 84252. From there head acr...

  
Track
Coastal Dublin - Donabate to Malahide
Onzy 5 days ago.
Circuit of Broadmeadows Estuary from Donabate to Malahide walk, Len: 12.9km, Climb: 115m, Area: Dublin Islands (Ireland)


RECENT CONTRIBUTIONS 1 2 3 .. 18 Next page >>