The earth’s molten surface eventually cooled down sufficiently to form a crust, under which gas and molten rock were trapped. The surface of the planet was continually broken up by exploding volcanoes, spewing out lava pools. Gradually a thicker crust was formed, entirely made up of volcanic rock. At that time, the first small continents were formed out of the sea of molten rock (magma), and the oceanic crust began to form. Gases and steam from volcanic eruptions began to thin out the atmosphere, causing violent electrical storms. Owing to the higher thermal regime, this was a period of tremendous catastrophes, explosions, with the continental crust forming then being blown apart, then forming again, partial melting, crystal formation and collisions, on a far vaster scale than anything seen since. The first micro-continents moved far faster and collided more frequently than today. There was a rapid process of generation and recycling of the continental crust. The formation of the continental crust was the most fundamental event in the history of the planet. Unlike the seabed, the continental crust is not destroyed by subduction into the mantle, but increases its total volume in the course of time. The creation of the continents was thus an irreversible event.

The earth is made up of a number of layers of material. The main layers are the core (divided into the inner and outer core), the thick mantle, and the thin crust on the surface. Each layer has its own chemical composition and physical properties. As the molten earth cooled some four billion years ago, the heavier materials sank to the earth’s centre, while the lighter elements stayed nearer the surface. The earth’s inner core is a solid mass, compressed by colossal pressures. The crust forms a thin layer around the semi-liquid mantle, like the skin around an apple. From the cool thin crust, down 50 kilometres, the temperature is about 800°C. Deeper still, at around 2,000 km, the temperature rises to well over 2,200°C. At this depth the rocks behave more like liquids.

This crust supports the oceans and landmasses, as well as all forms of life. About seven-tenths of the crust is covered by water, which is a fundamental feature of the planet. The surface crust is very uneven, containing huge mountain ranges on its landmass, and under water ranges in the deep oceans. An example of one is the Mid-Atlantic Ridge, which forms the boundary between four of the earth’s plates. The crust is made up of ten major plates that fit together like a jigsaw puzzle. However, along the edges of these plates “faults” are situated, where volcanic activity and earthquakes are concentrated. The continents are fixed into these plates and move as the plates themselves move.

At the border of these plates underwater volcanoes spew out molten rock from the bowels of the earth, creating new ocean floor. The seabed spreads away from the ridge like a conveyer belt, carrying with it huge rafts of continental crust. Volcanoes are the source of the transformation of enormous energy from the earth into heat. There are an estimated 430 active volcanoes at present. Paradoxically, volcanic explosions release energies that cause the rocks at the crust to melt. The earth’s crust (lithosphere) is being continually changed and renewed. New lithosphere is constantly being created by the intrusion and extrusion of magma at the mid-ocean ridges through the partial melting of the mantle (asthenosphere). This creation of new crust at these faults pushes the old floor apart and with it the continental plates. This new lithosphere spreads away from the mid-ocean ridges as more material is added, and eventually, the very expansion of the ocean floor leads elsewhere to it submerging into the earth’s interior.

This process explains the movement of continents. The constant subterranean turmoil in turn creates colossal heat, which builds up and produces new volcanic activity. These areas are marked by island arcs and mountain ranges and by volcanoes, earthquakes and deep ocean trenches. This keeps the balance between new and old, in a dialectical unity of opposites. As the plates themselves collide, they produce earthquakes.

This continuous activity under the earth’s surface governs many phenomena affecting the development of the planet. The landmass, oceans and atmosphere are not only affected by the sun’s rays, but also by gravity and the magnetic field surrounding the earth. “Continual change,” says Engels, “i.e., abolition of abstract identity with itself, is also found in so-called inorganic things. Geology is its history. On the surface, mechanical changes (denudation, frost), chemical changes (weathering), and, internally, mechanical changes (pressure), heat (volcanic), chemical (water, acids, binding substances), in great upheaval, earthquakes, etc.” Again, “Every body is continually exposed to mechanical, physical and chemical influences, which are always changing it and modifying its identity.”[5]

Under the Atlantic Ocean there is an undersea volcanic mountain chain where new magma is constantly being created. As a result, the oceanic crust is being enlarged, and is pushing apart the continents of South America and Africa, and also North America and Europe. However, if some areas are getting bigger, others must also be consumed. As the American continent is being pushed by colossal forces against the Pacific Ocean crust, the ocean plate is being forced to dip under America, where it dissolves, moves in currents, and eventually emerges – after millions of years – in another mid-ocean ridge.

These are not smooth, linear processes, but take place through contradictions and leaps of truly cataclysmic dimensions. There are times when the forces beneath the earth’s outer crust meet with such resistance that they are forced to turn back upon themselves, and find some new direction. Thus, for a very long period, an ocean like the Pacific can be enlarged. However, when the balance of forces changes, the whole process goes into reverse. A vast ocean can be squeezed between two continents, and eventually disappear, forced between and under the continents. Such processes have occurred many times in the history of the planet over 4,600 million years. Two hundred million years ago, there was an ocean – Tethys – between Euro-Asia and Africa. Today the only remnant of that ocean is part of the Mediterranean Sea. The rest of that great ocean has been consumed and has vanished beneath the Carpathian Mountains and the Himalayas, destroyed by the collision of India and Arabia with Asia.

On the other hand, when a mid-ocean ridge is closed (that is, consumed under a continent) then new lithosphere will appear in another place. As a rule, the lithosphere breaks through at the weakest point. Unimaginable forces accumulate over millions of years, until eventually quantitative change produces a cataclysm. The outer shell is shattered, and the new lithosphere breaks through, opening up the way for the birth of new oceans. In the present day, we can see signs of this process in the volcanic valley of Afar in East Africa, where the continent is breaking up and a new ocean will be created in the next fifty million years. In effect, the Red Sea represents the very early stages in the development of an ocean separating South Arabia from Africa.

The understanding that the earth is not a static but dynamic entity gave a powerful impulse to geology, placing it on a really scientific basis. The great success of the plate tectonics theory is that it dialectically combines all the natural phenomena, overturning the conservative conceptions of the scientific orthodoxy based upon formal logic. Its basic idea is that everything upon earth is in constant movement, and that this takes place through explosive contradictions. Oceans and continents, mountains and basins, rivers, lakes and coastlines are in a process of constant change, in which periods of “calm” and “stability” are violently interrupted by revolutions on a continental scale. Atmosphere, climatic conditions, magnetism, even the location of magnetic poles of the planet are likewise in a permanent state of flux. The development of each individual process is influenced and determined, to one extent or another, by the interconnection with all the other processes. It is impossible to study one geological process in isolation from the rest. All of them combine to create a unique sum total of phenomena which is our world. Modern geologists are compelled to think in a dialectical way although they have never read a single line of Marx and Engels, just because their subject matter can be adequately interpreted in no other way.

  1. Engels, F. Dialectics of Nature, 1946 edition, p. 163 and p. 162.