CHAPTER 5

HOW THE EARTH FELL APART


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"Speak to the Earth, and it shall teach thee."

-- Old Testament: Job, xii, 8.

What Shall We Call the Bits?

As we develop the theme of this book further, we will be dealing with portions of the Earth's surface of every size, from small islands like Rottnest, right up through the parts and wholes of present continents and on to the complete cap of continental material which once covered the whole of the smaller Earth.

The only name commonly in use for any of these areas is the word 'plate'. We will see shortly that this is not a particularly appropriate word. If a large plate is broken into a hundred pieces, is each of these a plate?

In this book, I will will using the general word 'domain' for areas of any size which have taken part in the Earth surface shifts described. This is on analogy with magnetic domains, the different magnetized areas of a magnetic material. These may be of any size, and if a large domain is split into a number of smaller parts, each of these is validly called a domain.

For larger domains, comparable in size to continents or the conventional tectonic plates, the form 'megadomain' will be used. However, a megadomain means something rather different to either a continent or a tectonic plate. The word 'continent ' means a large, contiguous area of the Earth's surface which is above sea-level. We will see that none of the present continents is a simple megadomain, instead all are aggregations of one or more megadomains with a number of smaller parts.

In my view, so-called tectonic plates are just the areas within strings of different domain boundary segments which are currently in active movement. Different boundaries of the same domain will usually be undergoing different degrees of movement, at any one time the majority of them will be relatively stationary.

Thus a tectonic plate is not a real entity in any permanent sense. Its extent is only defined from the strings of active domain boundaries, and in reality some of these will be so inactive as to be included only to make up a complete figure. Hence the boundaries of 'plates' are only arbitrary, and their subjective nature naturally leads to arguments as to where particular plates extend to, or whether they are really several smaller plates.

Proposition 5A

A tectonic plate is not a real entity in any permanent sense, but only the area within an arbitrary assembly of more or less active parts of domain boundaries

Aggregates of smaller domains have been identified in various parts of the Earth, and to these the word 'terrane' has been applied. These will figure later on in the book. While I believe that 'terrane' is a valid concept and word, for consistency the term 'microdomain' will be used in this book.

For the complete cap of continental material covering the whole surface of the smaller Earth, the term 'holodomain' will be used.

The First Megadomains

We have seen from Chapter 4 that it is reasonably clear which of the major present land areas were part of the southern megadomain, Gondwanaland, and which belonged to its northern counterpart, Laurasia.

Now we can go into the nitty-gritty of how, and why, it occurred. But first we need to look at some figures on land areas, which lead to a conclusion initially surprising, but obvious in retrospect.

It is accepted that Laurasia included most of Europe, North America, and Asia, and that Gondwanaland included most of Africa, South America, Australasia, and Antarctica. The land areas of these continents (in million square kilometres) is as follows:

First Approximation

 Laurasia

Gondwanaland

Europe

 9.9

Africa 

30.3

North America

24.4

South America 

17.8

Asia

44.8

Australasia

8.5

 

 

Antarctica

14.0

TOTAL 

79.1

TOTAL

70.6



We can see that the two megadomains were of roughly similar size, even on this crude first approximation. Refining these figures one stage more, we know that there is very strong evidence that India and Southeast Asia were part of Gondwanaland rather than Laurasia. These two regions have a total area of about 7.7 m sq km. Subtracting this from Laurasia and adding it to Gondwanaland, we get:

Second Approximation

 Laurasia

Gondwanaland

As above

79.1

As above

70.6

less India/SE Asia 

7.7 

plus India/SE Asia 

7.7

TOTAL 

71.4

TOTAL

78.3



On the second approximation, the two totals are a bit closer, but not satisfyingly so. Now is the time to bring in a point of detail of great importance.

Antarctica, the Fake Continent

We need to look more closely at the figure for Antarctica; it conceals a basic error which appears to have been ignored, in spite of readily available evidence. Antarctica is a fake continent. Much of its assumed land area is, in fact, sea -- or rather would be if the ice was melted. The South Pole itself lies some 1000 metres below sea level.

This is not in any sense new information. It appeared, for example, in the 4th edition of the National Geographic Atlas in 1975, from which Fig. 5.1 is derived.


Figure 5.1 shows the conventional outline of Antarctica, and within it, the areas which are probably 'real' land, in the sense that they would be above sea level if the covering ice was removed and the sea allowed to flow in. In fact, only the part of Antarctica below Australia appears to contain a real landmass, the part below South America is actually only a chain of small islands. We still don't have the full picture, but as an approximation it appears that the real land area of Antarctica is only about half the 14 million square kilometres usually quoted.

Proposition 5B

Antarctica is not a real continent, but an assembly of islands, with a land area probably totalling no more than half the 14 million square kilometres usually assumed

This point seems to have been completely ignored in previous reconstructions of how the continents fitted together in earlier times, whether on the old continental drift basis or using the newer expanding Earth approach. Nearly all these reconstructions have a great lumpy Antarctica stuck between Africa and Australia, and of course this strongly affects the matching.

Laurasia and Gondwanaland were Equal!

When we adjust the Laurasia/Gondwanaland figures for this new smaller value for Antarctica, we get:

Third Approximation

 Laurasia

Gondwanaland

As above

71.4

As above

78.3

 

 

less Half Antarctica

7.0

TOTAL 

71.4

TOTAL

71.3




and this agreement is excellent. Its relevance will be becoming apparent.

Of course, it is possible to go on into a Fourth Approximation. The areas of Central America, the Caribbean, California, Florida, Spain, Arabia, Atlas Mountains, Southern China, and Japan all contain a mixture of plant elements which make their positioning in either Laurasia or Gondwanaland a little less than certain. The exact land area of Antarctica is yet to be determined. Greenland is also partly a fake, as it is hollow, and the same may apply to other Arctic islands. But the general picture is clear --- Laurasia and Gondwanaland were close to having identical land areas.

Proposition 5C

The former megadomains of Laurasia and Gondwanaland had the same surface areas

On now to the actual course of events. Assuming that there was once a solid 'skin' of continental matter covering the whole surface of the Earth, and this Earth then expanded under the skin so it split into pieces, how might we expect this to proceed?

Formation of the Equatorial Girdle

Well, the first thing which might happen is that the skin would split in half along the equator, into two equal 'caps', leaving a depressed 'oceanic girdle' around the Earth. This would be reasonable, both from the point of view of symmetry (where else would the line of weakness be?) and from a factor relating to conservation of momentum which we will look at later. And as further supporting evidence, we have the marked equality of area of Laurasia and Gondwanaland.

Proposition 5D

The first major event in Earth expansion was the splitting of the holodomain in half, along the Equator, to form the two megadomains of Laurasia and Gondwanaland

There is considerable evidence for the past existence of such an 'oceanic girdle' , which has sometimes been called the Tethys or Tethyan Sea. In fact its existence has been a stumbling block to some of the earlier, pre-expansion theories of the development of the Earth. In Chapter 13 (on fossil fuels) we shall also see an important implication of this equatorial marine girdle, which will be referred to here as the Tethyan Girdle.

What Happened Before the Split?

In postulating the Equatorial Split as the first major event of Earth Expansion, it is reasonable to ask what happened before it, to make it happen when it did. Why did the Earth suddenly undergo this paroxysm of expansion?

I believe that there was no sudden event, the Equatorial Split was just a very obvious effect of processes which had been taking place for a long time previously. In this connection, we should look first at changes in the rate at which expansion has occurred in the past.

Carey has suggested [Carey, 1987] that the rate of Earth Expansion has been accelerating continuously during the measurable past. In earlier eras, the rate of expansion was slower, and the further you go back, the less the rate of expansion. It appears possible, in fact, that expansion has always been occurring during the Earth's physical evolution, but that the effects have only become really obvious as the rate has speeded up, especially in the last 200-400my .

It appears that the distinguishing feature of the Equatorial Split was that this was the first occasion during which the skin of continental material covering the Earth was stretched thin enough to split open and expose the 'oceanic' rock material underneath. According to this scenario, movements of the material covering the Earth's surface had occurred previously, but these had only served to thin out the layer of lighter continental material, and not actually breach it.

Proposition 5E

The Equatorial Split which created the two megadomains of Laurasia and Gondwanaland was notable for the first surface exposure of underlying 'oceanic' material, as the overlying continental material was thinned out by past expansion

We will pass on now to look at what happened subsequent to formation of the Equatorial Split, when Laurasia and Gondwanaland were themselves beginning to split into smaller parts. And here we can gather further evidence through looking at what happened to domains of different sizes; their size does seem to have had an effect on their subsequent behaviour.

Flight of the Microdomains

As an example, look at Fig. 5.2, a map of areas of occurrence of fossil and modern hickories, taken from 'Tree Ancestors', a most interesting book by Edward Berry [1923]. This can be compared with Fig.4.11 in the previous chapter, showing the current distribution of Carya, the pecan and hickories.

It appears that smaller land masses have travelled further from the Equator than have larger pieces to which they were once attached. This is reasonable if the larger pieces have centres of gravity close to the equator, so that the 'centrifugal forces' pushing part north and part south are more evenly balanced. On the other hand, a small landmass well north of the equator has no south-moving section to push against the north-moving urge, and so may be expected to move faster and farther north.

Notice that in addition to the modern areas, fossil remains of hickories have been found in Greenland, Iceland, Alaska, and even in tiny Svalbard (Spitzbergen), only a few degrees below the North Pole.

This leads to a most important point. The usual interpretation of Fig. 5.2 is that the climate in southern Greenland, Iceland, and the other fossil locations must once have been warm enough for hickories to grow there. While this may be true, the implied assumption that warmer climates once extended to much more northerly latitudes is not necessarily so. In reality, microdomains carrying these fossils may have individually moved north, out of warmer zones, after the fossils were deposited.

Proposition 5F

Fossils of warmer-climate plants found in areas with colder climates may have been carried there by domain movement

If this proposition is true, it does of course throw confusion and doubt into the whole area of studies of climate in past eras (paleoclimatology). The same is true of other aspects of geology and Earth sciences which assume current parts of the planet were always in the same positions as now.

Proposition 5G

All areas of the Earth sciences which implicitly assume a fixed Earth must be subject to detailed reconsideration in the light of possible domain movements



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Last update 2014 Nov 24