Talk:Stack (geology)

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Needs discussion of formations atop a marine terrace[edit]

The article leads one to believe all stacks are in the seabed, while in fact many are perched on marine terraces. The geologic process of formation of these terrestrial stacks needs to be discussed. Cuvette 02:39, 22 June 2007 (UTC)

Ball's Pyramid[edit]

Does Ball's Pyramid count as a stack or not? If it's the only bit left after the erosion of a much larger volcanic island, that seems to fit IMO. It was originally included as an example, then commented out and finally reintroduced through a picture, so either the picture goes or it stays and the text reappears. Any thoughts? Mikenorton (talk) 18:21, 20 April 2009 (UTC)

I was just thinking the same thing. I don't know any geology so I can't help either way but right now the wording is inconsistent with the photo caption. --Zvika (talk) 04:56, 17 September 2009 (UTC)
The feature would count as a stack but a volcanic stack, not one which has been eroded from the coastline.Fusion001 (talk) 19:51, 21 October 2009 (UTC)
I had similar thoughts re Rockall. Geopersona (talk) 18:12, 25 February 2012 (UTC)
There are some sources that describe Rockall as a stack [1], [2] [3], although the term islet seems better to me. There are other similar 'stacks' off northern Scotland such as Sule Stack, which is Lewisian gneiss. These 'stacks' are all remnant islands, derived from much larger areas of land originally. However, there seem to be enough sources describing them as stacks that we probably need to include them. Mikenorton (talk) 20:05, 25 February 2012 (UTC)

Merge[edit]

I've merged the content of Kekur as per the discussion at Talk:Kekur. Andreww (talk) 18:05, 22 August 2010 (UTC)

I don't really get this stacks thing. Please explain!!99.181.144.161 (talk)meha —Preceding undated comment added 13:45, 30 August 2010 (UTC).

Is this in reference to the merge or to the concept itself? If it's the concept, you might want to ask your question (and probably be more specific) at the science reference desk.—Ëzhiki (Igels Hérissonovich Ïzhakoff-Amursky) • (yo?); August 30, 2010; 15:09 (UTC)

Preferred rock types[edit]

The article currently asserts that Stacks typically form in horizontally bedded sedimentary or volcanic rocks particularly on limestone cliffs. These rock types' medium hardness means medium resistance to erosion. Apart from being somewhat clumsily written - are we right to place the emphasis on limestone here? The variations in erosion-resistance across different types of sedimentary rocks (and indeed volcanic rocks) is huge - and more often than not the propensity to form stacks will come down at least as much, I should have thought, to the extent and nature of jointing in the rock rather than its lithology. cheers Geopersona (talk) 18:10, 25 February 2012 (UTC)

Originally the text there just said limestone, which I attempted to generalise a bit. It seem to me that there are two different types of stack - remnant islands like Rockall that can be of any resistant rock type and the more classic type of stack left behind on an eroding cliffline, like the Old Man of Hoy, which tend to be generally of bedded (and jointed) rock (sedimentary or volcanic). However, I can't find any sources that support such a distinction, or that mention bedding or rock type, although jointing is considered important in generating sea caves that eventually lead to stack formation. Having said that, I just found the following "Small bays, narrow inlets, caves, arches, and stacks are usually the result of erosion along structural weaknesses, particularly bedding, joint and fault planes, and in the fractured and crushed rock produced by faulting. These features form in rocks that have well defined and well spaced planes of weakness, yet are strong enough to stand as high, near vertical slopes and as the roofs of caves, tunnels and arches. They are therefore uncommon in weak or thinly bedded rocks with dense joint systems (Trenhaile, 1987)." - so that's something to go on. Mikenorton (talk) 20:34, 25 February 2012 (UTC)

Too many examples[edit]

As with many other articles, the list of examples is starting to take over the article. The obvious thing is to start a list article, list of stacks, to put these in, leaving just a few very notable examples plus a link to the list article itself. Thoughts? Mikenorton (talk) 20:24, 21 May 2014 (UTC)