Originally posted by Helen:
We just put up this part of Barry's web page and thought those of you who like pretty pictures would be interested in it...
http://www.setterfield.org/secondvalley.htm
It might also interest geology buffs and those who are interested in possible hard evidence of some very rapid processes occurring during rock formation.
Barry starts off by saying:
"Very often we are told that most rock-forming geologic processes and layers are the results of extremely slow processes. But there are a few places on earth where the evidence is very much to the contrary."
This is untrue. You have often been told that
many rock forming processes are slow, not that most are. Also, there are not a
few places on earth that provide evidence of alternatively rapid processes. There are many. And, believe it or not, mainstream geologists have actually noticed this.
The point is that rapid processes occur all the time in geology and have not gone unnoticed by geologists. Your problem is that, often, there are very long intervals between the rapid events, often consumed by slower events or hiatuses in the record.
Having said that, the evidence you cite from Second Valley is not evidence for rapid processes. In fact, quite the opposite could be interpreted.
The simple explanation for the convolute laminae in hard rocks is 'low strain rates.' Such rates of strain are quite capable of producing the features you have noted and they would require lengthy time intervals to provide the total strain evident in the rocks that you have observed.
In addition, the rocks you say must have been deformed rapidly had to have been:
1)deposited at some prior time, having an even older source area, and
2)eroded and covered by more recent sediments, that are
3)even now being eroded to expose the metamorphic exposures that you see in Second Valley.
And I dare say the the appearance of Second Valley has not changed much since the first humans visited. Hence, long times and multiple rapid/slow processes can be logically inferred.
Now, you might say, as YECs often do, that the rocks were really deformed while in the soft-sediment state. If so, you should explain to us how deformed metamorphic minerals occur, along with other metamorphic textures such as rotated porphyroblasts.
Barry goes on to say:
"It looks like what is seen here all formed at once, while all the materials involved were still plastic, and then hardened together at the same time. The slate is not cracking at the bends. Nothing is cracking at the bends."
Yes, all earth materials can be plastic under the proper conditions of temperature, confining stresses and strain rate. The fact that the crests of folds do not show brittle deformation attests to this. Rapid deformation would, in direct opposition to Barry's statement, result in rupture of the rock. I have even seen fracture cleavage developed during soft sediment deformation. Again, if the sediments were soft, the metamorphic mineral grains would show no internal stress or outward strain, as they often do in metamorphic terranes.
Having said this, I also have to say that I have not been to Second Valley so I cannot be certain just what the mineral textures tell us. However, there are thousands of similar locations, of very different age scattered all over the world, and I doubt that they are significantly different.
(rocks show up in the bathtub, in the sink, in corners, in plants, on her dresser, IN her dresser, in her pockets, EVERYWHERE) LOL