The following is my translation of an article called: Geologische Umschau von Dr B Lindemann. It appeared in a German popular science magazine, Kosmos Handweiser für Naturfreunde 1909, Heft 3, Seiten 65-70. Footnotes accompanied the original piece, and I've implanted them into convenient points of the text. Any article should be read with intelligence and an appreciation that the stand of knowledge can change. A piece written a century ago has had plenty of time to fall victim to new research. Among the casualties are the suggested numbers of years for past ages. They're way too low. More intriguing is the postulated 'Tropical' Ice Age. Continents have since been found guilty of moving around, and the now tropical areas were polar during the Permian. There are other points as well, so don't assume this reflects the current understanding. If you're intending basing your homework on this, then you're teacher will be left very puzzled.
For me, such contrasts add to the charm. I'm not aware of any previous translation.
Trevor Dykes.

Geological review by Dr B Lindemann

The valid view up until now maintains the Earth is contracting. The Earth is warm and became warmer the deeper one goes, -at a depth of 50km, according to a reliable calculations, it already reaches a molten condition, -space however, is cold, monstrously cold, perhaps not far from the temperature of 'absolute zero' (-273°C): how could it be otherwise than for the Earth to constantly give up warmth to space and, consequently, to commensurately shrink is step with the increasing coolness?

The extent of this shrinkage has even been calculated. At least 100 million years have elapsed since the Silurian period of the history of the Earth, and the radius of the Earth could have diminished by 50-60km. That would be about half a millimetre per year.

Shrinkage, however, would affect the inner Earth more, assuming it to be a glowing liquid, than the already solid crust. This consideration has led to the thought that the shrinkage of the crust could not keep pace with that of the inner Earth, which would disappear more rapidly and then be surrounded by an overly large shell. However, due to gravity, the crust could not maintain such a situation. It would partly break up and come to rest again at the core; but, as it is too large, other parts would be torn from their surroundings, be powerfully shoved over and through each other, and would be pressed up high above the earlier level of the surface. In this manner 'folds' and 'crumples' would result in the face of Mother Earth and, although these would not be of much significance in comparison to the size of the globe, they could appear to we small people as vast chains of mountains or folded mountains.

At least, that is the theory of mountain building which is almost generally accepted today but, due to recent research on the conditions inside the Earth, it is not one we can any longer be loyal to. Textbooks like to use the example of a dried out apple when it comes to explaining the 'shrinkage theory'. "As the skin will gradually become too large, so it crumples and sinks towards the disappearing flesh, and that is also how the inner Earth behaves." At first sight, the comparison appears nice and appropriate, but its weaknesses soon come to light. Even the comparison between such a small thing as an apple and the vast Earth, with all the undoubtedly powerful reactions underway within it, is something which can hardly be taken seriously. And then the main thing: the apple consists of a weak, pliant mass whereas the inner Earth, as has been shown by research into earthquakes, consists of a material which is not beaten by steel in terms of resilience and rigidity, and may well significantly outperform steel. A comparison between two physically so various things can hardly enable one to explain the other!

The main prop of the 'shrinkage theory', until now, was the impossibility of coming up with a convincing alternative explanation for the loss of heat from the Earth into the coldness of space. However, with recent research into the abundance of radium in the Earth's crust*, one can speak only with difficulty about a progressive cooling of our planet. The following train of thoughts leads to the same result.

(* See 'Radiologische Umschau' von Dr MW Meyer, Kosmos 1908, Heft 1.)

As has earlier been shown in this paper**, one has good reasons to assume that the inside of the Earth is divided into two zones: a thin molten mantle close against the hard crust, and a powerful core comprising most the mass of the globe, and with a very remarkable composition (quality).

(** 'Geophysikalische Umschau, Kosmos 1907, Heft 10.)

The core is filled with enormously hot gasses, and these gasses are forced so closely together by the vast pressure, that they are practically like a solid body with the rigidity of steel. More about this can be read in the previously mentioned 'Umschau'. These mighty, thick gaseous masses are rules by enormously strong tensions, and the attempts of the gas to spread out must produce an immeasurably increased glowing heat to such a degree, that we could hardly imagine it. It appears completely impossible that a mass like this could shrink. On the contrary: it would expand at the slightest opportunity. Such opportunities are provided by volcanic eruptions which produce a reduction in the molten mantel around the core. Significant quantities of lava are transported to the surface of the Earth or to the proportionately cooler layers of the crust, and solidify. Through these means, material is lost to the molten zone only to be replaced from further in, from the core. The core expands uniformly, pushes some of its mass gradually upwards into an aggregate condition between a gaseous and molten state without, however, altering its essential quality. Details of this process are undoubtedly involved and not yet fully understood. One thing should be borne in mind: the 'expansion' of the core cannot be imagined as some form of quick, sudden movement. The rigidity of the material in the deepest strata of the Earth necessitates an incomprehensibly slow, consistent transference from a tough gas to an at first no less tough, very dense area of mantel.

The result of this is as follows: the innards of the Earth will be a still indefatigable storage heater for a very long time. The Earth as a whole is not shrinking but rather, it gains in volume due to the internal molten mass spreading increasingly the higher it rises. Shrinkage as the basis for a theory of mountain building is no longer tenable; in its place comes something different, in which the tendency for an expansion of the Earth's core is a given factor of significance.-

But, some readers will object, geology has demonstrated that it used to be much warmer on the Earth than it now is! During the old Tertiary, palm forests grew in Central Germany populated by apes, lemurs and numerous other animals which, today, are only known from the tropics. Greenland had the climate of California; as well as beach, poplars, oaks and so on, sycamores and magnolias grew there; Spitzbergen was about as warm as it now is here. In the even older Carboniferous age, the whole Earth appears to have been ruled by a uniformly warm climate. Is such evidence not convincing? Does it not lead us to having to accept a progressive cooling? If it is really now much cooler than during the fairly recent Tertiary, must we not accept the prophets are correct, and that a "cold death" faces us in a not too distant future?

We do not believe that these pessimists are correct. Cold periods have often occurred in the history of our planet; one can in no way explain them by a progressive cooling of the Earth. As far as the climatic developments of the Earth can be followed, climate conditions have generally swapped around. Once occurred an immeasurably long period with a very even tropical warmth spread over the surface of the Earth, and then came shorter periods during which, like today, there was a pronounced division of the Earth into climatic zones, and sometimes it has even been so cold, that large areas have been covered by inland ice and glaciers. It is instructive to follow these remarkable changes more closely.

If the hypothesis of a progressive cooling of the Earth were correct, then such a temperature must have prevailed in the age of original organic life, the so called 'Eozoic' or 'Precambrian' era, that today's average temperature at the tropics must have been then exceeded by many times. One must consider: the Tertiary age, when it was far hotter than today, was at the most a million years ago, and the 'Eozoic' age lay at least 200 million years ago.

Should one multiply the probable temperature decrease since the Middle Tertiary, about 10° Celsius, by 200, then one would arrive at an average temperature for the 'Eozoic' age of 2000°C!! The proponents of the cooling hypothesis would dispute the reliability of this calculation, but they would have to admit that the temperature during the original time of life would have been so hot, that any plant or animal life on land would have been impossible. Good! there are absolutely no secure traces of terrestrial organisms from then or some later periods. However, the waters of the original oceans must also have been barbarically hot. We know that algae can function in North American geysers at temperatures of 85°C, and flagellates in a laboratory can survive 70°C heat; but we have to ask ourselves in astonishment how colonies of polyps (the extinct stromatoporoids found in Colorado) could have survived in that hot soup, or sealilies (found in Brittany) or crabs (found in Montana). There are only two possibilities: either the age of those strata has been set far too high, or the hypothesis of progressive cooling is wrong.

Luckily, some new discoveries quickly help us out or the dilemma. To our great surprise, we learn that during the time of 'glowing' prehistory there were -glaciers already! Deposits have been discovered in three distantly separated parts of the world; in northern Ontario, at Baranger Fjord in Finnmark and on the Yang-tse in China, glacial slate, moraines, drumlins, glacial clay. What should we say to that? It appears that the climatic conditions during that almost unimaginably ancient era of prehistory were not all that different from today, at least as far as the temperature and cold zones of the northern hemisphere are concerned.

Following the Eozoic era came the Paleozoic, and that began with the Cambrian period. We know as good as nothing about the climatic conditions. Corals, whose presence could provide clues as to tropical conditions, are completely absent from Cambrian strata. The strangeness of the predominant tapes of animal, trilobites or Urkrebse, do not even allow presumptions to be made, as to whether they more favoured ward or cold conditions. Only one detail is perhaps suitable for throwing a certain amount of light onto the climate of this period. Significant thicknesses of red sandstone were deposited over wide areas of the surface of the Earth, sandstone entirely of the kind of the common Buntsandstein in Central Germany, and this is generally held to have been produced in deserts, the result of a warm and very dry climate. If this conclusion also applies for the whole of the Cambrian age, then this would be a remarkable difference from the proceeding Carboniferous age which, on the contrary, is marked by an almost global spread of a very wet, greenhouse-like climate.

Already in the Silurian, the period which followed the Cambrian, an upturn appears to have begun. The first land plant occur; they are horse tail trees and ferns, close relatives of forms which x million years later made up the Carboniferous forests. We can assume that these Silurian plants required a moist, persistently warm atmosphere in order to flourish. Also significant is that coral reefs were then found within the polar circle; remains have been discovered in present day Greenland, in the extreme north of Russia on Novaja Semlia and the New Siberian Islands. And when one also takes the worldwide ranges of many animal forms into account, eg. the brachiopods***, then probability suggests a globally warm climate during the Silurian period, even in the Arctic areas.

(*** a group of animals derived from worms.)

The following period, the Devonian, is marked by the same climatic characteristics and indeed, the cosmopolitan ranges of many animal forms is even more apparent. In all probability, the same uniform humid climate ruled virtually uninterrupted for millions of years from the Silurian, through the entire Devonian on until the end of the Carboniferous time. Indeed, it reached its highest point during the latter. "The climate of the Carboniferous", wrote E Kayser in his 'Lehrbuch für Geologie', "must have been mild and very damp and also remarkably uniform for large parts of the surface of the Earth. The reasons for this are not yet clear to see; the fact is, however, that the Carboniferous flora stretched in a meridianal direction from the equator up to the Zambezi and far up into the northern polar circle (Bear Island, Spitzbergen), and in a latitudal**** from North America through the whole of Asia across to Europe. A general verdict based upon the components of the flora and the recorded insects, suggests at least a frost free climate of exceptionally insular character. A similar conclusion is prompted by the character of the Carboniferous ocean fauna, which shows a surprising uniformity from the most distant points of the Earth.

(**** the direction of the Earth's latitudes.)

The astonishing wealth of the Carboniferous forests means that the air of that age must have had a higher concentration of carbonic acid than is the case for the present. A very acceptable explanation has been provided for the source of this richness of carbonic acid. Ash is known, carbon is a volcanic gas which is not only released in great quantities from the vents and fissures of active volcanoes, but is also found in concentrations where volcanoes are long extinct (eg, in the Eifel), where numerous sources of carbonic acid, Mosetten and Säuerlingen (Note: that may be carbon, but I'm not sure) quall from the ground. That precisely the Carboniferous is characterized by its vitality of nature and a wide range of volcanic eruptions, a strong increase in the amount of atmospheric carbonic acid is not surprising. However, whether this increase in carbon dioxide was responsible for the uniformly warm climate, as the Swedish physicist Arrhenius believes he has shown, is very debatable. According to Arrhenius, the atmospheric increases in carbon dioxide and the temperature coincide, and this is because the thicker atmosphere strongly deflected rays from the coldness of space. Recently, the correctness of this conclusion has been challenged and, when one considers that the Secondary Age, of which we shall speak further later, was also generally a warm time but also one of an almost complete absence of volcanic activity, then the explanation offered by the Swedish researcher is not entirely satisfactory.

The Carboniferous reached its end with the paradisiacal uniformity of the climate. However, occurrences during the middle of this period were already suggesting that, at least in a few lands, a more changeable climate must have been developing. A mighty chain of mountains arose in Western and Middle Europe, from Spain to Silesia, Poland and Austria, which did not compare unfavourably with our Alps in terms of height and was significantly more widespread. Later, at the end of the Carboniferous and during the transition to the following Permian, mountain folding took place over a much wider area of the globe. Eastern and Southern Russia, Armenia, Central Asia, Japan, Sumatra, and significant areas of North America (the Appalachians) and South
Africa experienced a complete recasting of their topography. It hardly needs stating that the build up of such widespread bodies of mountains must have had negative influences upon the climate across broad areas of land. The following evidenced themselves quickly during the Permian. In place of an evenly warm climate, astonishingly stark extremes occurred. If that were not enough, nature appears to have reversed the usual rules of distribution of heat and cold. We see the remarkable show that lands to both sides of the equator were much cooler than in our climes; so cold, that large areas were sought out by glaciers. The Permian Ice Age of tropical areas is an absolutely secure result from geological research. The Indian subcontinent, South Africa and Australia were all particularly violently affected, but traces were also left in Brazil and Argentina. In contrast, as far as we know, the northern temperate zone was spared. While the plant remains found here show it was also much colder, we search in vain in the Permian strata of the German Rotliegenden and the Zechstein for traces of glaciers. On the contrary, the thick deposits of plaster show a totally different tendency. Such deposits could only have built up in salty lagoons and internal seas which, like mighty salt pans, were left by slow evaporation in a warm, dry climate. From this we can deduce a climate something like that presently prevailing in the Caspian Sea.

As the Permian cold period gave way, there began a very long age of relatively uniform warmth for the Earth. This was the so called Secondary or Mesozoic age with the periods Triassic, Jurassic and Cretaceous. Mountain building and volcanism were almost completely quiet during the many millions of years of this time; undisturbed, the ammonites were able to radiate into an astonishing wealth of types in the warm seas while, on land as well as in water, reptiles with many genera and species grew to be the dominant class of animals. This is not the place to follow the climatic conditions of the Secondary in all details, but it will suffice to report that there was a gradual yet clear tendency towards the establishment of the climatic zones of today. Nothing of that can be seen during the Triassic, but the beginnings are shown during the Jurassic and, in the Cretaceous, there was already a sharp division between the warmer south and colder north. The border ran through France and Germany, but one should not imagine that the climate of Northern Germany corresponded to the present one. It was still significantly warmer. Chalk on the island of Seeland is almost entirely composed of the crushed shells of corals, and corals have also been found in the Schreibkreide of the German Baltic. On the other hand, we know that Greenland and Spitzbergen were covered with leafed forests during the Cretaceous, and all this indicates that the temperature differences between north and south cannot have been all too great.

The same undoubtedly applies for the old Tertiary, during which the European area was sometimes much warmer than had been the case at the end of the Cretaceous. Forests of coconut and date palms, laurel and fig trees grew in England, and palms even spread to East Prussia and, as for Southern Europe, the average temperature in that area has been estimated at 25°C! However, it was already cooler by the middle of the Tertiary. The Earth began to grow unstable, and all the processes known from the Carboniferous and Permian were repeated. New major ranges of mountains arose, the main folding of the Alps, the Carpathians and Pyrenees, the Apennines, Caucases, Himalayas and probably the Cordilleras as well, were all folded during the recent Tertiary. Volcanic activity reawoke and produced enormous masses of lava stone in all lands. And again, at the close of this powerful revolution, we see the Earth sought out by an Ice Age. The temperature decrease at the end of the Tertiary is ever more rapid, sensitive mussels and snails, which then lived in today's North Sea, show the seas were warmer in the older deposits; then these are pressured and replaced by purely Arctic forms. The Ice Age set in, and Northern Europe and North America were most badly hit, and the various regions of the world with newly arisen mountains feel to glaciers.

The ice retreated for long periods on a number of occasions and, in warmer glacial interludes, the animal and plant kingdoms took repossession of the devastated lands, but renewed advances of glaciers forced life back out of hardly conquered areas. Whether today we have finally passed through the Ice Age? We do not know. Only one thing is sure: the cold period, under which the Earth of the youngest Tertiary suffered, is still exercising its rule. There is no noticeable sign that the opposing climatic zones are losing their sharp distinctiveness. However, to conclude from this that the present situation is unalterable, and that the Earth will sooner or later fall to a cold death, appears very short-sighted. Then we would be right to remember that the present cold period has not lasted for such a very long time! A half- or even an entire million years is of little weight in the geological history of the Earth! The Earth has endured through two cold periods in earlier ages, and why should it not also endure through a third, this present one?

But what are the requirements for this? The question as to the causes of remarkable changes in climate is not easy to answer. All of the many theories to resolve this problem have so far failed. It is probably not necessary to seek an explanation for all phenomena in 'cosmic' causes such as, for example, movements of our solar system through colder and hotter areas of space or the like. The reasons may be much more likely found on the Earth itself. Probably, a stark change in the distribution of water and land would suffice, in order to radically alter contemporary climatic conditions. Particularly for Europe, the situation is as follows. During the warmer Tertiary, parts of the North Atlantic were dry land; a landbridge connected Ireland with the Faros, Iceland and the New World. This would block the cold polar currents. Meanwhile, the southern coasts of our continent were washed by a tropical sea which, as well as encompassing the Mediterranean, covered the whole of North Africa and stretched across to the Indian Ocean. The Alps were only islands in this 'South Sea' which, periodically, completely filled the deep plains of the Upper Rhine. Should similar conditions return in the distant future, then a time could arrive when even Germany would once more become a land of palms.

An index of more of my translations of old Kosmos articles can be found at:

Kosmos Translations Archive
kosmostranslations.htm

A number of Mesozoic (and post-Mesozoic) location summaries can be found at Localities.