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Great Unconformity

30 August 2023

Gary sent in a link to a New Scientist piece on the Great Unconformity – a huge piece of missing geology. As the source was paywalled, and I was too late to buy a copy from the newsagent, I looked up the Wiki. Go to https://en.wikipedia.org/wiki/Great_Unconformity … in order to get an idea of what Gary was referring to. The Wiki is often criticised because it has citizen editors who can write up reviews of a subject that are out of date, or worse. This is especially true of controversial subjects – such as climate change. A dedicated band of editors patrols the Wiki looking  for anything contrary to the mainstream mantra – and deleting the offending material as soon as it is spotted. However, geology does not seem to inspire the same kind of fanatic. Geologists tend to have their feet on the ground. Hence, the link above can be  considered reliable.

Having said that, catastrophism in geology is another matter. Even staid old SIS has been the subject of some Wiki editor deleting material posted. So yes, we are not flavour of the month, as they say. It is too boring and tedious to keep upgrading our Wiki entry  as the fanatics are many and we are few. One cannot help somebody with a closed mind, or a shill for the Blob. Life is too short. Eventually, the truth will out.

There are actually many unconformities observed in geological strata – but the Great Unconformity is frequently applied to one observed by James Hutton at Sicar Point in Scotland, and the other by Wesley Powell in the Grand Canyon. Here is the rub. The Wiki tells us these are examples of where contact between sedimentary stratas of greatly different ages, origin, and structures – are missing. It is assumed sediments are laid down all the time. One group of sediments should be followed by another sedimentary layer. Igneous rocks, for example, are an intrusion into this process. We are even told that these periods of geological time are sufficiently long enough for mountains to form and erode away. As far as uniformitarianism is concerned – that is a lot of missing time. However, they take it in their stride and there are said to be perfectly good reasons for the missing strata. In a catastrophist scenario, sediments can be laid down in great upheavals. Not all of them of course as sediments are laid down in in lesser upheavals – such as volcanic eruptions and major storms etc. The gaps can be simply as a result of missing time between one major catastrophic event and another. In such a scenario sediments would form much as they do in our world but would not be preserved as they were not buried. Hence, no actual sedimentary strata would have been preserved.

In the case of the Hutton unconformity we are talking about an interval between 425 and 340 million years ago. Both sides of this gap have sedimentary layers associated with water. In the first instance, the sediments are said to have been laid down by turbidity currents. These can of course just as easily have been laid down quickly. However, uniformitarians choose to interpret them as several layers, laid down over a long period of time. This is not an attempt to squeeze the gap but simply what mainstream teaches. Slow and inexorable laying down of geological layers. Unconformities are in fact the counter argument. If uniformitarianism was really taking place, now and in the past, there would be no gaps. Geologists would have found the missing layers. After all they have had about 150 years to come across the material missing from the rocks.

Likewise, the second event, or sediments associated with it, also has a watery feature. The Wiki tells us, rather than water overflowing the land, it is rationalised as being laid down by rivers and streams, forming pools and marshy zones. In a catastrophist scenario water overflowed the land and then receded, leaving behind the pools and marsh. The gap here is around 80 million years. A long period in which no major upheaval occurred – and earth was safe from space rocks.

Powell’s unconformity in the Grand Canyon is the one that sparked Gary’s interest. This was a continent wide unconformity – running right across North America. It can be seen in the Grand Canyon as that is a big hole in the ground. A lot of strata can be seen. It is suggested by mainstream, that North America was submerged by a shallow sea. More water associated with the event. It could also be evidence of an outwash event. It is also dated at the Cambrian/Ordovician boundary. Here the unconformity is said to be a gap of 175 million years of missing time. However, in othr places the gap is estimated to be as much as 725 million years. That means the uniformitarian dating mechanism has thrown up an oddity. How can the gap vary by such a large amount of  time. In other places the gap is as much as 1.2 billion years – which caught the eye of Gary. The disparity is clearly associated with how the unconformity is analysed, and dated – by the slow gradual process favoured by geologists. One might even visualise sedimentary strata dated over a long period of time when in reality it may have been laid down in days, or even hours. In that situation one can see how the unconformity has different lengths of time in different places.

However, read the link. Interesting stuff – but also read between the lines. Geologists are not silly. They have recorded the unconformity because that is what the rocks are telling them. Geochronology is probably littered with gaps in the strata, most of which is ironed out by dating the laying down of sediments as a slow process. Gaps are just periods of earth history in which nothing  catstrophic happened. Or that is an alternative way of looking at it.

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