Through his involvement with the Ilmenau mine, Goethe was stimulated to study the realm of the minerals, rocks, and types of stone, as well as the superimposed strata of the earth's crust. In July 1776 he accompanies Duke Karl August to Ilmenau. They wanted to see whether the old mine could be started up again. Goethe also devoted further care to this matter. Through this there grew in him more and more the urge to know how nature goes about the formation of its great stone masses and mountains. He climbed high peaks and crept into the depths of the earth in order “to discover the most immediate traces of the great shaping hand.” On September 8, 1780 from Ilmenau he shared with Frau von Stein his joy at learning to know creative nature also from this side. “I am living now body and soul in stone and mountains, and am very happy about the broad perspectives that are opening up to me. These last two days have conquered a large area for me and can suggest a great deal. The world is taking on for me now a new and vast appearance.” More and more the hope takes hold in him that he will succeed in spinning a thread which can guide him through the underground labyrinth and give him an overview in the confusion (letter to Frau von Stein on June 12, 1784). Gradually he extends his observations over other regions of the earth's surface. On his journeys in the Harz Mountains he believes he recognizes how great inorganic masses take shape. He ascribes to them the tendency “to divide in manifold regular directions in such a way that parallelepipeds arise which in turn are inclined to split diagonally.” (See the essay, “The Shaping of Large Inorganic Masses.”) He thinks of stone masses as interpenetrated by an ideal latticework, and this in a six-sided way. Through this, cubic, parallelepipedic, rhombic, rhomboidal, pillar, and plate-shaped bodies are cut out of a basic mass. He pictures to himself within this basic mass forces at work which divide it in the way that the ideal lattice-work makes visible. As in organic nature, so Goethe also seeks in the stone realm for the idea at work in it. Here also he investigates with spiritual eyes. Where the division into regular forms does not come to appearance, he assumes that it is present as idea in the masses. On a journey in the Harz Mountains which he undertakes in 1784, he asks Councillor Kraus, who is accompanying him, to execute pastel drawings in which the invisible, ideal is made clear by the visible and brought to view. He believes that what is actually present can be truly portrayed by the painter only when he is attentive to the intentions of nature which often do not emerge clearly enough in the outer phenomenon. “... in the transition from the soft into the rigid state, a separation results, which either applies now to the whole, or which occurs in the most inward part of the masses” (Essay on “Formation of Mountains as a Whole and in its Parts”). In Goethe's view a sensible-supersensible archetypal picture is livingly present in organic forms; something ideal enters into the sense perception and permeates it. In the regular formation of inorganic masses there works something ideal which as such does not enter into the sense-perceptible form but which does nevertheless create a sense-perceptible form. The inorganic form is not sensible-supersensible in its manifestation but only sense-perceptible; but it must be considered to be an effect of a supersensible force. It is an intermediate thing between the inorganic process whose course is still governed by something ideal but which receives a finished form from this ideal, and the organic in which the ideal itself becomes sense-perceptible form.

Goethe thinks the formation of composite rocks to have been caused by the fact that the substances which were originally present in a mass only as idea are then actually separated out of each other. In a letter to Leonhard on November 25, 1807, he writes, “I gladly admit that I still often see simultaneous operations where other people see a successive operation; that, in many a rock which others consider to be a conglomerate, a rock brought together out of fragments and fused together, I believe I see something differentiated and separated out of a heterogenious mass and then held rigidly together by consolidation.”

Goethe did not reach the point of making these thoughts fruitful for a larger number of inorganic developments of form. It is in accordance with his way of thinking to explain even the ordering of geological strata by ideal formative principles which are inherent in substance by its very nature. He could not adhere to the then widespread geological views of Werner, because Werner did not know such formative principles but rather traced everything back to the purely mechanical action of water. Even more repugnant to him was the Volcanism which Hutton had presented and which Alexander von Humboldt, Leopold von Buch, and others defended, which explained the development of the various periods of the earth by mighty revolutions, brought about by material causes. This view lets great mountain systems shoot suddenly forth from the earth by volcanic forces. Such enormous tours de force seem to Goethe to contradict the being of nature. He saw no reason that the laws of earth development should suddenly change at certain times and, after long, ongoing, and gradual activity, should manifest at a certain point in time as “heaving and shoving, thrusting up and crushing, hurling and smashing.” Nature seemed to him to be consistent in all its parts, so that even a god could change nothing about its inborn laws. He considers its laws to be unchangeable. The forces at work today in the formation of the earth's surface must by their very being have worked in all ages.

From this viewpoint he also arrives at a view, in accordance with nature, as to how the blocks of stone which are to be found strewn about near the Lake of Geneva and which, to judge by their composition, were separated from far-away mountains, got there. He was confronted by the opinion that these rock masses were hurled there by the tumultuous eruption of mountains located far inland. Goethe sought forces which can be observed today and which are able to explain this phenomenon. He found such forces active in the formation of glaciers. He needed only to assume now that the glaciers which today still bring rock from mountains into the plains once had an immensely greater scope than at present. They then carried the rock masses much farther away from the mountains than they do in the present day. As the glaciers receded again, these rocks were left behind. Goethe thought that the granite boulders which lie about in the low plains of northern Germany must also have arrived at their present location in an analogous way. In order to be able to picture to oneself that the areas which are erratically strewn with boulders were once covered by glacial ice, one needs to assume an age of great cold. This assumption became the common property of science through Agassiz, who came to it independently and in 1837 presented it in the Swiss Society for Natural Scientific Research. In recent times this age of cold, which broke in upon the continents of the earth when a rich animal and plant life was already developed, has become the favorite study of eminent geologists. The details which Goethe brings forward about the phenomena of this “ice age” are unimportant in the face of observations made by later researchers.

Just as in his assumption of an age of great cold, Goethe is led by his general view of nature to a correct view about the nature of fossils. It is true that earlier thinkers had already recognized these entities as the remains of organisms from former ages. But this view was so long in becoming the generally dominant one that Voltaire could still consider fossilized mussels to be freaks of nature. After gaining some experience in this area Goethe soon recognized that the fossils, as remains of organisms, stand in a natural relationship to those earth strata in which they are found. That means that these organisms lived during those epochs of the earth in which the corresponding strata were formed. He expresses himself in this way about fossils in a letter to Merck on October 27, 1782: “All the remains of bones of which you speak and which are found everywhere in the upper level of the earth, stem, I am fully convinced, from the most recent epoch which, however, compared to our usual reckoning of time, is immensely old. In this epoch the sea had already receded; on the other hand rivers still flowed, of great breadth, yet relating to the level of the sea, not faster than now and perhaps not even as fast. At the same time, the sand, mixed with lime, settled into all the broad valleys which little by little, as the ocean sank, became free of water; and in the middle of them the rivers dug only shallow beds. At that time elephants and rhinoceroses were at home here upon the exposed mountains, and their remains could very easily be washed down by woodland streams into those great stream basins or ocean flats, where, more or less permeated with minerals, they were preserved and where we now dig them up by accident with the plow or in other ways. It is in this sense that I said earlier that one finds them in the upper level, in that, namely, which the old rivers washed together, as the main crust of the earth's surface was already fully formed. Now the time will soon rome when one will no longer just throw fossils all together but will classify them according to the world epochs.”

Goethe has repeatedly been called a precursor of the geology founded by Lyell. Geology also no longer assumes mighty revolutions or catastrophes in order to explain how one earth period arises out of another. It traces earlier changes of the earth's surface back to the same processes which are still at work now. But one should also be aware of the fact that modern geology brings forth only physical and chemical forces to explain earth formation. That Goethe, on the other hand, assumes formative forces which are at work within the masses and which represent a higher kind of formative principles than physics and chemistry know.