Putting The Earth Back Together [NU007]
Ben Franklin Centre for Theoretical Research
PO Box 27, Subiaco, WA 6008, Australia.
"We have been living in an Age of Analysis, when we have found out a great deal about
many different aspects of the world in which we live. But now is the time to move into an Age
of Synthesis, when we will put together all this body of knowledge"
We have now laid the groundwork for the task of trying to fit back together the vast
spectrum of domains of every size, to reconstruct the original holodomain which once covered
the whole of the Earth's surface.
It would be nice to present here the complete picture, but, alas, that is quite impossible. It
will require years of painstaking work by many people, plus probably the need to go out into
the field and accumulate new evidence, before all the arguments will be settled and we feel
that we really have got the thing right. All we can do here is make a start on the new area of
investigation called Domainography, by putting together some working rules and giving a few
The Rules of Domainography
The first aim of the approach must be to keep it as simple as possible -- we will expand
on this further in NU017. When the broad outlines are established, then will be the time
to find the exceptions to the rules and possibly to refine or extend those rules. At the same time,
we know that the general rules will be extracted from a mass of individual, detailed examples.
What general rules should we have? We can start off with the following:
RULES FOR HOLODOMAIN RECONSTRUCTION
Rule 1. Larger landmasses are composites of many domains.
Rule 2. As domains broke up, the relative positions of the pieces stayed the same, while their distances apart increased.
Rule 3. There were no large rotations of domains.
Rule 4. Smaller domains have moved further than larger ones.
Rule 5. Domain splitting was according to the normal behaviour of materials.
Rule 1 is a basic assumption. Rule 2 simply means that if Domain 26A was to the
east of Domain 26B before Domain 26 split, then 26A will always be more or less to the east of 26B, even though they may end up hundreds or thousands of kilometres apart.
Rule 3 is an interesting one. At this stage it is purely a rule-of-thumb. There is, in fact, a physical law, called the Coriolis Force, which does cause rotation of bodies moving away from or towards the Equator (this determines the direction of rotation of cyclones and the way water swirls down the plughole). But all instances of domain rotation observed to date seem small enough to make their existence questionable.
We might expect this rule to be broken when a smaller, irregularly-shaped domain impacts
against a larger one at an oblique angle. India looks as if it might have rotated a few degrees
anticlockwise when it ran into Laurasia and made the Himalayas. However this apparent
effect could be illusory, caused by differences in the angle of viewing a landmass at different
Rule 4 is also an observed rule of thumb, derived from the distributions of plants and
animals which we have already examined. For Rule 4 to apply, it obviously must be physically
possible; there is no way a microdomain is going to force its way through a megadomain it has
run into, to keep up with its fellow which was off to one side of the megadomain.
Rule 5 is an important one, with many consequences. It just says that all domains are made
up of masses of rocks which have known physical properties, and the domains will obey
normal physical laws of every sort. The fact that we may not have a complete picture of some
of these laws does not affect the point.
We already invoked Rule 5 when it was pointed out that the deep ocean trenches could not
have been formed by pushing one slab of rock against another (see Proposition 3C) -- such
an act could not create a gap between them. Another consequence is that the new boundary
formed when a domain was torn apart could not be especially complex.
Such a new boundary might well vary from very clean and straight (such as that of the coast
of Israel and Lebanon) to somewhat irregular and jagged. But normal physical forces would
not permit a break to be formed in the shape of a deeply concave bay, such the Gulf of
Carpentaria on Australia's north coast. This must be a composite of some sort, there must be
at least two domains involved in its formation. This also applies to any other 'complex'
coastline or domain boundary, complex on a scale beyond that of erosional effects. We have
already seen, for example, how major peninsulas involve at least two different domains.
This is important enough to extract as a new rule:
Rule 6. Areas with deeply concave edges or other complex shapes must have been formed
from at least two different domains.
In addition, there is one more rule which has justification to be explained later (NU008):
Rule 7. All mountain chains, both on land and under the sea, represent domain boundaries.
The last item in our armoury, before we look at actual re-assembly, is a useful technique.
The Rubber Band Technique
There is a convenient visual approach we can use in this. Look again at some of the plant distribution maps given in Chapter 4. Assume all the land areas have been divided up into domains.
Now regard the distribution boundary as a rubber band, and shrink this band down. It will tighten, and pull together all the domains which were once connected by the early distribution range of the plant genus or species. This will give a preliminary picture of how the domains involved once fitted together on the pre-expanded Earth.
This technique can be used not once for each domain, but hundreds of times -- once for
each plant species, genus, or family represented on it. It can even be used for 'races' within
a species, and if the genetic patterns of individuals are available, say through the isozyme
analysis method, it can be used with them too.
Of course this technique will also drag in a ring of domains which do not form part of the
original distribution, but instead are just current neighbours of original domains, neighbours
onto which the plants have spread through natural dispersion processes. These neighbour
domains need to be discarded.
The width of the neighbour ring to be discarded depends on how specific the level of plant
description is, and what the likely rate of natural spread is judged at. To deal with the last part
first, we will set up the last of our rules, which is an attempt to put numbers to Proposition 2A:
Rule 8. Natural rates of spread of a plant species average no more than 1 metre per year
At first sight, this estimate seems incredibly low. One metre per year is only 1 km in a
thousand years, which seems very little, however it is also 1000 km in a million years, and that
is quite a lot. Many plant species lie entirely within a range which is less than 1000 km across.
We have already suggested (Proposition 2I) that the half-life of a species is around one million
years, so, in fact, this figure does seem to be of at least the right order of magnitude.
On the matter of plant description specificity, the broadest grouping, that of plant family,
is too broad to be of much help here. Most modern plant families, such as the Fagaceae (which
includes the oaks, chestnuts, and the northern and southern beeches) date back to the early part
of the Cenozoic Era, 50-70 my ago. This would give them the opportunity to spread 50-70,000 km, much more than the distance right round the Earth (40,000 km). However, again
it does seem of the right order of magnitude, if anything favouring a lower figure than that in
We have never put a figure to the half-life of a plant genus, such as Araucaria, but it would
be somewhere between the species half-life and the known age of the family it is part of.
Suppose we put a value of 10 my to this half-life. Then the average distance we would expect
a genus to spread naturally would be 10,000 km, and the most a species would extend would
be 1,000 km.
Although the Rubber Band technique presented above was a simple visual technique, it
could in fact be developed into a computer approach, in which the width of the discardable
neighbour rings could be easily varied to see the effect on the final re-assembly. I suspect that
in many cases the width of these rings could be cut down to less than the distances implied by
the above estimates without affecting the validity of the technique.
For example, look again at Figure 2.1, which shows the distributions of seven different
Canarium species (the map for the whole genus is Fig. 4.7). It would be my contention that
all the areas within the range of the most widely-spread species, number 1, C. littorale, were
once joined and the species has ended up in the different major islands and peninsulas
principally through Earth expansion. This is even though the name of the species means it is a sea-shore plant, and the seeds are designed to float and could well cross from island to island,
making this is a worst-case example.
The current range of the species is about 2000 km across. If the islands were all pushed
together by tightening the rubber band, it would drop down to a width of around 1000 km --
which is equivalent to an overland spread from a single centre of only 500 km.
Now we can look at different areas of the current world, suggesting how they may have
been related in past times before the Earth expanded, and applying all the above rules. As
usual, the main evidence comes from the distribution of plant species, genera, and families.
Australia appears to contain at least two megadomains, probably with a common boundary
running roughly north-south through Lake Eyre and down to Spencer Gulf. In addition, it has
either a long thin wedge or a microdomain shuffle belt running down the east coast, to the east
of the Great Dividing Range.
The east coast geology looks more like a shuffle belt. Certainly there is a marked
movement of species down the east side of Australia. Typical 'tropical' genera which extend
as far south as northern New South Wales include Canarium (Fig. 4.7) and Carissa. The
Bunya Pine (Araucaria, Fig. 4.4) of southern Queensland (but with an outlier in North
Queensland, and most of the family in New Guinea) has also presumably been carried down
on this belt.
The whole of the northeast coast of Queensland has a complex rain-forest flora with strong
links with the northwest coast of South America. Virtually every major family present in that
area of South America has close relatives in northeast Queensland, often in the same genus
(Pouteria, Syzygium, Endiandra, Litsea, Cryptocarya). The excellent fit of eastern Australia
against western South America has already been remarked upon, the evidence is overwhelming
that these two areas were once in contact.
In fact the evidence for this contact is much stronger than that for the Africa-South America
contact which has been taken for granted since the earliest days of the Continental Drift idea,
with its origins with Francis Bacon, right back when the Spanish and Portuguese explorers first
mapped the southern Atlantic coasts.
This contact is a major distinction between the Continental Drift approach and its later
Expanding Earth derivative. In the former, Australia is invariably placed at the opposite end
of Gondwanaland to South America, and usually has adjacent New Guinea poking out into an
unmapped sea. In the latter, Australia and New Guinea nestle snugly against South America
and Central America, and the strong family links are easily explained.
Although the Myrtaceae family which contains the Eucalypts is well represented in South
America (Eugenia has representatives in both domains), the typically Australian Eucalyptus
is not. In fact the eucalypts are not especially common in the northeast Queensland rainforest,
and this domain may have been separate from the rest of Australia at one time. Certainly the
eucalypts appear to have evolved after the two megadomains separated. This separation
presumably took place before the migration of monkeys from west Africa into northern South
The whole of the northern coast of Australia shows strong floristic links with adjoining
areas of Asia. Nut-bearing genera such as Canarium and Terminalia are typical examples,
although these extend well beyond the immediate area. One interesting genus is Horsfieldia,
a relative of the nutmeg. This has around 80 species scattered through southeast Asia,
including Indonesia and southern China, and one species, H. australasica, found only in the Northern Territory and the Gulf of Carpentaria. It has been recommended for development as a commercial nut species .
Australia also has species of Myristica (nutmeg) and Zizyphus (jujube or chinese date) matching those found in southern Asia as far north as the Himalayas. The jujubes are notable for the fact that they thrive in arid inland areas and could not be expected to cross sea barriers.
The west coast of Australia shows typical features of microdomain flight, as we have seen
with Rottnest Island and various peninsula formations. As far as more distant links are
concerned, a major feature is the strong connection between southwest Australia and South
Africa, as shown especially through the Proteaceae family. These, typified by the beautiful
Proteas of South Africa and the Banksias of southern Australia, provide probably the strongest
southern link between the two continents; there are hundreds of species in each. On the nut
side, the Van Riebeck almond, Brabejum stellatifolium, of South Africa, is closely related to
the woody pears (Xylomelum) of Western Australia.
There are plenty of links between northwest Australia and eastern Africa, as for example
Canarium (Fig. 4.7). Recently a new species of blind hunting spider was discovered in the Cape Range peninsula of the west coast , and its nearest relative was noted as originating in southern Africa.
On balance, it seems likely that southwest Australia was once in actual contact with what is now southeast Africa. The fit is quite good. It is possible that Madagascar intervened, but this has probably come down from further north -- see later. The separation of Australia and Africa must have been of middle age -- not ancient, but before the evolution of the eucalypts.
It should be pointed out here that if Australia was in contact with Africa and South America
on the west and east, and these two other continents were themselves in contact along their
Atlantic coasts, this means a very tight fit of these three continents around the South Pole must
have occurred, if their shapes were the same as now. This would have left very little room for
Antarctica, even the small one which we have seen is actually there (Proposition 5B). All this
is evidence both of re-seaming and domain shifting in the megadomains. It also implies a pre-expanded
Earth somewhat smaller than that usually assumed, closer to 50% of the present
diameter instead of the 55-60% sometimes assumed.
Direct evidence of modern plant links between Australia and Antarctica is virtually
lacking, because Antarctica proper supports no higher plants, and there are no major islands
between Australia and Antarctica. As for the island State of Tasmania, this is a typical island
microdomain, with a flora easily represented as having evolved from a much earlier 'tropical'
assembly, carried well to the south. It has Nothofagus, the Southern Beech, which it shares
with the New Guinea highlands and with New Zealand and southern Chile. It has one
representative of an ancient conifer genus, Dacrydium, most species of which are found in
Malaya and Indonesia (Malesia), but which has representatives in New Zealand, New
Caledonia, Fiji, and Chile.
The distribution of Dacrydium is a good starting point to generalize some inferences into
formal propositions. No conifer is noted for its ability to spread by sea, and it appears
impossible to explain this distribution rationally except by assuming that all the above areas,
now tens of thousands of kilometres distant, were once linked. The distributions, and the
current characteristics of the species involved, follow naturally from the following Propositions:
In the early part of the current (Cenozoic) era, 50-70 my ago,
the immediate ancestors of most of our current plant genera were
This evolution took place in one or more 'equatorial bands'
of physically interlinked domains extending right round the
Earth, with easy spread of species along the bands
The climatic conditions in these equatorial bands were
closer to those of currently temperate areas than to modern
One note to this last Proposition -- it is based on the twin observations that there are a few
families with representatives of the same (or closely-allied) genera in both southern-hemisphere
and northern-hemisphere temperate areas, and that when representatives of these
genera still exist in equatorial areas, they appear to have mostly retreated to the cooler uplands.
Examples include the Beeches, represented in the north by Fagus and in the south by Nothofagus, with the latter having species in the uplands tropics, the willows (Salix), and the
Junipers (Juniperus). Most instances of these dual-temperate genera fall easily into this
pattern. The inference is that the families involved are the more ancient ones, and the corollary
is that typical 'tropical' families are of more recent origin.
Typical 'tropical' plant families are of relatively recent
origin, less than about 50 my old
New Zealand and the Pacific Islands
In spite of its clearly temperate location, New Zealand is noted for the 'tropical' appearance
of its plants. We have seen that it has one of the most southern representatives of the
Sapotaceae, it also has representatives of Eugenia, Aleurites, Freycinetia, and a palm,
Rhopalostylis, as well as a host of other 'tropical' genera. However, it has no native eucalypts
or wattles (Acacia, and evidently was not attached to Australia in recent times. It has very few
deciduous trees, another indication of non-temperate origin.
In fact, in spite of the modern separations, New Zealand has links perhaps closer to Chile
than to Australia, particularly in the South Island -- it is quite possible that the two major
islands were not so closely linked in the past. It seems likely that both islands have moved
south relative to larger landmasses, possibly to different extents.
The islands of the Pacific show all the features of equatorial-band development and domain
flight which we have come to expect. These islands are not tricky to reassemble into their pre-expansion
conformations with a high degree of precision, purely by repeated rubber-banding
of all their native species. The general picture is unmistakably one of a tropical development
band stretching from Indonesia across to Central America, split into thousands of smaller
parts, with a few islands on the northern and southern limits of the band showing equatorial
flight into more temperate areas.
In the rubber-banding, it is important to question (Proposition 6A) the usual assumption,
that many species have been introduced. The Hawaian group, in particular, has many species
assumed to have been introduced, but which fit excellently into the expansion pattern. An
example is the legume Leucaena, with 50 species in tropical America and two others stretching
across through Hawaii to Polynesia. In fact is is probably more sensible to reverse the
procedure, and determine whether or not a species has been introduced by seeing whether or
not it 'rubber-bands' in a normal way. This test is quite independent of any historical evidence,
such as the assumed spread of the coconut across the Pacific through the canoes of the
The match of a plant's current distribution pattern with other
local isocons gives evidence of whether or not the plant was
introduced by man
South and Central America
South America appears to contain two large domains, the bigger mostly made up of Brazil
south of the Amazon, and the smaller the Guiana Highlands area to its north. It also has the
most prominent domain shuffle belt in the world running down its west coast. There is an area
of accreted islands or re-seamed domains east of Panama and extending over much of
Columbia and Venezuela.
We have already seen how the western shuffle belt has acted as a raft to carry species
southwards. A good example is the Pygmy Coconut, Jubaea spectabilis, which is confined to an area of central Chile (Fig. 4.14). Of course palms are typically tropical, but this one is
the most southern and cold-resistant palm of all, able to withstand snow.
Like all palms, Jubaea is of Gondwanan origin. There are, however, a number of species
of Laurasian origin which have managed to jump onto the shuffle belt. Figure 7.1 shows the
distribution of modern and fossil occurrences of the walnuts, Juglans. It is taken from Berry's classic book .
Fig. 7.1. Distribution of walnuts: modern (black areas) and fossil (shaded)
Notice that the modern walnuts occur right across what we can regard as the South
Laurasian Equatorial Band -- they are obviously Laurasian -- and that the fossil occurrences
(clearly somewhat sweepingly brushed in) extend up to Greenland. We know now why this
is so. Notice also that occurrences of modern walnuts are shown in the Caribbean and
extending down the Andes as far as Ecuador and Peru. These are also readily understandable,
typical microdomain band shuffling.
But look again, and notice a large area shown for walnut in eastern Brazil, on the coast.
This does not fit our pattern at all. I believe that it is an error.
Everyone can make mistakes -- there may well be some in the maps I have put together
myself -- but the important point here is that we can use the reasoning developed so far to
predict that this walnut placing is an error, and that prediction can be checked. Ability to
produce predictions, and their verification, is one of the most important facets of any scientific
Another interesting point which emerges, if you look at the various plant species of
northern South America, is that species and genera on the Amazon Basin side are often quite
different to those on the western coast. As an example, look at Figure 7.2, taken from Mitchell
, which shows the distribution of species of Anacardium, the cashew genus.
Fig. 7.2. Distributions of some species of Anacardium
The Anacardiaceae family which includes the cashews has representatives across the
tropics, including the Australian cashew, which however is no longer placed in the genus, but in Semecarpus. The former is now restricted to 10 species, the nine shown
in Fig. 7.2, and the cashew nut itself (A. occidentale), which occurs in the same area as the rest.
However, the closest relatives to Anacardium are not species of Semecarpus, but the three
species of Fegimanra which grow in tropical West Africa -- again fitting the pattern precisely.
The point being made here is that neither the cashew genus itself, nor its close relatives,
occur on the Andes coast of South America except in the extreme north, so it is presumably
a fairly recent passenger on the shuffle belt. The genus does extend much further southwards
on the east of the Andes, right down to northern Uruguay.
The walnut and cashew maps also help to define the status of the Caribbean islands and 'mainland' Central America. The walnut does not occur on the mainland, only on the islands. The converse is true for the cashew. Clearly there has been mixing of Laurasian and Gondwanan species in this zone, but the general position is consistent with the assumption that both parts are made up of a collage of microdomains which formerly lay right across the
boundary of the two megadomains -- part of what we have called the Tethyan Girdle. Detailed reconstruction involves only repeated application
of the rubber-banding technique.
It also seems that the present land bridge between North and South America is not
particularly old, and previous land connections may have been further east. Mainland Central
America is a clear aggregation of different domains, showing very obvious peninsulas and
large lakes formed through the chance conjunction of different island outlines. The Galapagos
islands off the coast of Ecuador have cacti (Opuntia) closely related to those of Mexico, and
have been shifted southwards.
The relation of South America to Australia has already been discussed. The link between
South America and Africa is obvious and inarguable. But even here, we can perhaps add a
little, on relative ages.
The Brazil-West African connection is strong. We have seen it with the oil palm (Fig. 4.3)
and with the cashew (Fig. 7.2). The connection can be shown again and again, through
different plant families; a further good example is the custard apple genus, Annona. This is most widely represented in northern South America, although there are a few species right
across tropical Africa and down the east coast. There is also a close relative, Asimina, which
extends from Florida up the east coast of North America -- of this more later.
But when you look further south, for connections between Argentina, Uruguay, and
southern Africa, the links are quite weak. This can be seen from the Proteaceae map, Fig. 4.1,
which has a notable blank area in southeast South America. The inference is that the southern
gulf between Africa and South America opened up well before the northern separation.
Africa and the Indian Ocean
Africa appears to be a relatively simple construction. It contains a number of large domains
-- these could be represented as Nubia, Congo, Kalahari, Somali, and North and South Sahara.
Most of these appear to have undergone some shifting and re-seaming, giving rise to features
such as the Adamawa Highlands between Nigeria and Cameroon.
The most obvious domainographic feature of Africa is the east coast. This is another
shuffle belt, not as dramatic as that of South America, but considerably more complex in the
sizes and nature of the domains involved. These have all moved southwards, leading to such
typical features as the many long, thin lakes. The Ethiopian Highlands and those surrounding
Lake Victoria could probably be accorded the status of separate domains.
The plant distribution pattern is fairly plain -- most families have bands of genera and
species extending along the tropical lines of latitude, with extensions southwards along the
east coast. The coffee genus, Coffea, is a typical example, as are the African examples of
In the north and east we run into the Tethyan Girdle, in this case including Spain, Italy,
Greece, Turkey, and the Mediterranean islands, all mixtures of Laurasian and Gondwanan
elements, with the former predominating. From the plant distributions, the Canary Islands are
clearly Gondwanan and the Azores Laurasian. The Atlas mountains in northwest Africa are
made up of several aggregated microdomains.
On the northeast, the major Arabian domain has separated off in the past and come back
into contact, ending up with the triangular Sinai microdomain jammed in the gap. Arabia,
which impacted with Laurasia to form the Zagros mountains, is shown by the plant
distributions to be a Gondwanan domain. But it probably separated off relatively early, as it has its own genera within the common families, such as the carob, Ceratonia siliqua, in
the legumes. It even has its own families, such as the pomegranate, Punicaceae, with only one
genus and two species, one of which is confined to the tiny island of Socotra in the Gulf of Aden.
India was indisputably part of Gondwanaland, and positioned against the east African
domains, but finding its exact former position is complicated by the fact that these domains
have been shifted south, possibly to differing extents.
Madagascar was probably positioned against where Mozambique is now, but again with
the complication that the northeast half of Mozambique may have been shifted south relative
to the southwest half. Madagascar has coffee species, which fits in well with the pattern.
Another excellent 'tie-in' genus is Adansonia, the boab or baobab family. This has one species
growing right across north-tropical Africa and down the east coast, extending also to India (supposedly 'introduced by Arab traders'!), and a second species native to the Kimberly area
of northwest Australia. But the big concentration, some 8-10 species, is in Madagascar.
Application of rubber-banding to Madagascan species will reveal its former connections, and because the island has many unique species related distantly or closely to those elsewhere, it should also be possible to work out when the different splits occurred, whether anciently or more recently. Of course the various edges of this domain were probably formed at different times.
The major link across from
east Africa and the Mascarenes
through India, southeast Asia,
Indonesia and across the Pacific to
Central America has already been
shown. An excellent subject for
rubber-banding is provided by the
Seychelles islands north of Madagascar.
These tiny, scattered islands
include some with towering
granite cliffs, virtually unique for
isolated oceanic islands, and clear
evidence of their 'continental' origin.
Fig. 7.3. A Coco-de-Mer nut
The Seychelles has a number
of endemic species (confined to
that area), in the genera Acalypha,
Begonia, Carissa, Dillenia (elephant
apple), Diospyros (persimmon),
Eugenia, Ficus (fig),
Grewia, Pandanus (screwpine),
and Pittosporum, all of which are
typical of the major link. It also
has the unique Double Coconut palm or Coco-de-Mer, Lodoicea, which has the largest seed
in the world, weighing up to 20kg. It takes seven years for the fruit to mature, three years to
germinate . The nut bears an astounding resemblance to portions of the human
female anatomy (Fig. 7.3), so much so that observers could quite understandably assume that
some cosmic prankster has been at work!
We have already identified some of the domains which make up the present North
American continent, which is of medium complexity. The major domainographic features are
the marked movements of shuffle belts or other domain aggregates north, on both sides of the
These shifts have carried palms up into California and Florida, and representatives of the
Sapotaceae up into Florida (Fig. 6.1). Florida also has representatives of the Gondwanan custard-apple family, the Annonaceae. These include both Annona itself (the genus of the
soursop, cherimoya, sugar apple, sweetsop, and most other custard apples) and also a genus
restricted to North America, Asimina.
This contains several species, but the only one well known, even in North America, is the
American Banana or Pawpaw (this is quite unrelated to the papaya, Carica papaya, which is
also called a pawpaw in some parts of the world). The Asimina is said to be the largest native
fruit in North America, good specimens weighing up to 500g. This again is a reflection of its
origin, the larger fruits all originated in Gondwanaland -- we will go into the reason for this
Asiminas grow over wide areas of North America, principally on the Mississippi domain
and the Atlantic domain (the coast from Florida to New York). Their distribution is evidence
that the genus was split off from the rest of the family some time ago. The boundary between
Asimina and Annona is reasonably distinct, running across northern Florida, and indicates that
Florida itself is a fairly recently accreted island domain.
Other domains which could be distinguished in North America include the Rockies,
western Mexico, Laurentia and three or four other large areas in continental Canada. Presence
of the Great Lakes shows interaction of a mess of microdomains, but the most complex area
of all is the west coast, which will take much study to sort out in detail.
Alaska is a complex of microdomains, as are the islands of northern Canada and, beyond
them, Greenland. The Aleutian islands, stretching from Alaska right across the North Pacific
to Asia, provide a very graphic illustration of fragments falling from the movement of the huge
hinge formed as the North Pacific opened up. The Aleutians, and the Alaska Peninsula with
which they terminate, appear to parallel Tierra del Fuego and the islands and submarine ridges
which sweep down from South America to Antarctica, in that they represent the oldest ends
of a microdomain shuffle belt. Both these shuffle belt ends show divergence from the usual
equatorial-flight patterns, and indicate that this pattern of behaviour may not always apply in
Propositions relating to equatorial flight of domains may
lose validity at high latitudes
North America also shows a similar pattern to South America, in that plants native to the
west coastal strip appear to 'intervene' between those east of the Rockies and the relatives of
the latter across the Pacific. There is a strong link between the Texas-southern Mississippi
flora and those of eastern Asia which appears to 'jump' over the west coast flora. This can be
seen in the distribution maps of Pistacia (Fig. 4.10) and Carya (Fig. 4.11). The 'jump' is very
obvious in Figure 7.4, from Berry , showing the distribution of the magnolia family.
Fig. 7.4 Distributions of genera of the Magnolia family
Try explaining the distributions in Figure 7.4 on the basis of migration across Bering Strait
land bridges! There are also many other examples in Berry , often with distribution
maps, showing the same pattern with such diverse genera as Tulip tree (Tupilifera), Sweetgum
(Liquidambar), Tupelo (Nyssa), and Sassafras.
This pattern is not confined to plants. The existence of relational links between the fossil
dinosaurs of China and western North America is well known, and is the subject of current study. What is interesting is that the American dinosaur occurrences are mostly
east of the Rockies, especially in the Canadian province of Alberta.
Of course all these points
confirm that the western shuffle belt has moved north along the coast, driving a wedge between
the main North American flora and their counterparts at the same latitudes on the Asian coast.
Europe is a mess. The only major domain which it contains, covering the USSR west of
the Urals and the North European Plain over as far as Germany, is structurally part of Asia
(although it has undergone some re-seaming, along the Central Russian Uplands and the Volga
Heights). Everything else is accreted and distorted domains and microdomains.
Running all along its south it has the scattered parts of the Tethyan Girdle -- the band of
island domains left from the original split of the holodomain into Gondwanaland and Laurasia.
European domains in this band include Spain, Italy, Greece, the Mediterranean islands, and
on to Turkey and the Central Asian republics of the USSR south of the Caucasus. All these
domains have predominantly Laurasian rather than Gondwanan flora, and so should probably
be classed with Laurasia. Also probably included with them is Ireland.
Ireland has, in its south-west corner, native occurrences of the Strawberry-Tree, Arbutus
unedo. This also occurs right across the Mediterranean, and other species in the genus extend
the range eastwards into the USSR (along the Tethyan Girdle) and, in the usual pattern, across
the Atlantic (including the Azores) into Mexico and southwest USA (there is a concentration
of seven species in Mexico).
The inference is that Ireland once lay in this band, and in fact, Ireland does fit quite snugly
against northwest Portugal. Britain is a most complex mishmash of microdomains, and France, Germany, central Europe and the Balkans are also much re-worked, the most
prominent feature being the Alps, formed when Italy collided with the northern domains.
To the north, Denmark, Norway, Sweden and Finland clearly consist of several domains
pushed together. The Scandinavian mountains show marked dissection through the action of
glaciers, which brings us to an observation concerning the Ice Ages.
When looked at from the viewpoint of plant distributions, the whole of northern Europe
is notable for the poverty of its plant species. It has almost no plant genera confined to its
boundaries, and comparatively few endemic species. This makes the application of rubber-banding
to the area more difficult than for most, and also raises the question of why the area
should be botanically sparse.
It appears that the answer to the last question lies in the Ice Ages. These were very recent
in geological terms, only 10-110,000 years ago (0.01-0.11 my). There seems no doubt that
glaciers formerly extended well south of their present European distribution, reaching
southern Britain, for example. Inevitably, a consequence of being overrun by massive glaciers
is the wiping-out of plant life in the area overrun.
Northern Europe has a relatively low level of plant diversity
because much of it was cleared of living plants through the action
Of course, when the glaciers retreated, vast areas of blank ecological niches were exposed,
and plants came in to colonise these niches reasonably quickly. But because the ice ages were
not so very long ago -- not only within the era of the species of man, but butting right up against
the development of civilization -- there has just been insufficient time to develop the diversity
of species and families which exist elsewhere.
It might be asked why the same situation does not exist across the whole of the temperate
parts of the Northern Hemisphere. To some extent it does, in that colder areas are relatively
poorer in plant diversity, but there is also another possibility. That is, that the recent ice-age
glaciers were not centered on the North Pole (as is usually implicitly assumed), but were
displaced more onto the European side for some reason.
Ice-age glaciers were not centered on the North Pole, but had
an area of influence displaced over into northern Europe
We have already seen that all the domains along the southern boundary of present-day Asia
-- including Arabia, India, Indochina, and southern China -- are Gondwanan 'borrowings'
since accreted to Laurasia. The Iran-Afghanistan domain is probably also one of these
borrowings. The Tethyan Girdle which shows up in the Americas and Europe apparently
either was never formed or was absorbed. There is a parallel formation, which includes the
island domains and peninsulas of Indonesia, Malaya, and the Philippines, but in this the Gondwanan influence is predominant.
In the main mass of Asia, north of the Gondwanan components, extensive re-seaming and
shifting of domains has taken place, especially in south and west Siberia and in China. These
actions have given rise to the many mountain ranges and to the strings of long lakes -- such
as Baikal and Balkhash -- and to the Turfan Depression in northwest China.
Fig. 7.5. Needles, cones and nuts of the
Siberian Stone Pine
The Siberian area is notable for having the largest isocon envelopes currently
existing on our planet. Stretching across the vast plains are huge areas in which the ecological conditions are relatively uniform, and so a particular plant species may come to have a very wide extent. One of the most prominent plants in this respect is, of course, a nut tree, the Siberian Stone Pine (Pinus sibirica).
This plant extends densely over more than 50 million hectares . The potential for producing nuts is huge, as a large tree may produce 1500
cones each year. The average biological harvest of nuts from each hectare reaches 800 kg, so the potential annual yield of nuts is 40 million tonnes. This is many times the total weight of all nuts which figure in annual world
From the domainographic viewpoint, the most interesting area in Asia is the Pacific Coast.
This shows extensive evidence of domain flight. Japan and Korea, though rich in Laurasian
flora such as oaks (Quercus), also have Gondwanan components such as yams (Dioscorea)
and cycads, which have clearly come up from much further south. Both show the typical north-south
oriented island or peninsula form, as do Sakhalin and Kamchatka to their north.
Southern China is one of the most floristically diverse regions of the world, with dense
intermixtures of Laurasian and Gondwanan components. Any proposed boundary line would
be open to argument, but it could lie somewhere along the line of the Nan Shan range.
As elsewhere, extensive equatorial flight has taken place along this coast. The whole of
Manchuria and southeast USSR has apparently shifted north. The position is made more
complex by the fact that domains of every size have been involved; we already saw in NU005 (Fig. 5.3) how the northeast USSR coast was a mass of microdomains. Instead of a
straightforward shuffle belt like that of South America, we have a great mingling and jostling
of large and small domains.
Plant distributions reflect the northward movement. A good example is the genus
Actinidia, which contains the kiwifruit, Actinidia deliciosa. The kiwifruit, once called the
chinese gooseberry, is one of 40 species in the genus, which is distributed not only in China
(and across to Burma) but also north, right up into Siberia, where there are some very cold-hardy
species. As well as Actinidia, the Actinidaceae family contains the genus Clematoclethra, with 10 species confined to China, and the big genus Saurauia.
In Asia Sauraia overlaps the southern range of Actinidia, extending through Burma (six
species) as far east as Nepal. But Sauraia is also well represented in America, with species
running from southern Mexico through Central America and right down the west coast as far
as Chile. The genus is absent from the Caribbean and almost absent from the Guianas and
Brazil. Again this is an absolutely typical pattern, the family showing strong links across the
north equatorial Pacific, and strong equatorial flight, northwards in Asia and southwards in
The Polar Regions
Because of the paucity of living plants in the polar regions, it is hard to apply standard
rubber-banding techniques to these areas. However, some information can be got from studies
of fossil plants and of animal distributions. Although difficult to apply, studies of marine flora
and fauna may also be productive.
Having looked at where domain movements have taken place around the planet, we are
now in a position to move on to the effects of these movements on the local landscapes -- how
they got their ups and downs.
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
(Full list of references at NURefs)
. Edward W Berry. Tree ancestors. Williams & Wilkins, Baltimore, 1923.
. Alex Harris. Spiderman links blind hunter to lost continent. The West Australian/ Oct 4, 1988.
. Dennis A Hearne. Some nut trees of the Northern Territory. West Australian Nutgrowing Society Yearbook/ 2 p43, 1976.
. Guy Lionnet. The double coconut of the Seychelles. West Australian Nutgrowing Society Yearbook/ 2 p6-20, 1976.
. John D Mitchell. The cashew and its relatives. New York Botanical Garden: Memoir 42, 1987.
. A T Savel'ev. Nedrevesnaya produktsiya lesa [Non-timber forest products]. Lesprom, Moskva, 1980.
NU008: Making Mountains Out Of Movements
NU006: More Distributions And Evidence
Go to the NUSite Home Page
Version 1.0, printed edition ("Nuteeriat: Nut Trees, the Expanding Earth, Rottnest Island, and All That...", Planetary Development Group, Tree Crops Centre, 1989).
Version 2.0, 2004, PDFs etc on World Wide Web (http://www.aoi.com.au/matrix/Nuteeriat.htm)
Version 3.0, 2014 Sep 21, Reworked from Chapter 7 of "Nuteeriat" as one article in a suite on the World Wide Web.