APPLICATION OF MORPHOMETRY TO STUDIES OF THE EARTH'S RELIEF AND STRUCTURE The relief of the lithosphere, similar to its inner structure, reflects the most important events in the development of our planet.
Studies of this natural chronicle have contributed considerably to our knowledge of the history of the Earth's development. Yet, even now many unsolved problems remain, one of which concerns tectonic movements and the relief forms conditioned by them. This problem has been discussed by many authors and numerous hypotheses have been advanced; nevertheless no satisfactory solution has thus far been found. Our work represents another attempt to find possible approaches to the solution of this important problem. This paper presents the preliminary results of our work and describes some of the patterns discovered.
The object of our study will be the relief of the lithosphere. The term "relief" is used to cover the entirety of all surface forms of the lithosphere*, including convex and concave surfaces and plains of various geological structures and origins, forming complex combinations with one another and bearing complex relationships to their environment (Piotrovskii, 1959, 1961).
Our definition of relief leads us to regard the lithosphere, as well as its relief, as a complex but at the same time integral natural formation, whose development obeys general laws and which is connected by complex interrelationships with its environment, i. e., the Earth's external and internal shells. Furthermore, the lithosphere and its relief may to a considerable extent be regarded as the "products" of the interaction of processes taking place in the external and internal shells. The litho sphere and its relief reflect the results of the interaction of energy arriving from interplanetary space (for instance, from the Sun) with the energy enclosed in the bowels of the Earth.
At the same time the entire Earth, being a cosmic body, is closely related in its development to interplanetary space and obeys certain general laws of the evolution of matter which have not yet been completely deciphered.
The effect of terrestrial and cosmic factors which are reflected in the lithosphere and in its relief manifests itself in various ways; furthermore, it varies in time and space. It may also vary in scale and may be composed of quantities of dissimilar orders of magnitude. Obviously, the weaker the effect of any given factor, the weaker also is the process brought about by this factor; the briefer the effect of the given process, the smaller its effect on the development of the Earth including its relief; the more limited its spatial distribution, tha smaller the area on which the "traces" of its manifestation may appear. On the other hand "minor processes" or "forces" may cause large-scale changes in the structure of the Earth and the Earth's crust, and in its relief, when they act together over long periods of time to produce a combined effect.
The genesis of relief forms is discussed in detail in specialized works; at this point we shall concentrate our attention on the dimensionality of these forms.
The Earth's relief is a complex combination of a variety of forms whose dimensions vary widely. The largest form is represented by the Earth itself while the smallest investigated forms may be represented by the very small-scale forms of sand ripples produced on sandy surfaces by wind, small waves, or weak currents.
The dimensionality of the relief forms — their length, width, vertical development (height and depth), steepness of their slopes, etc. — is studied in a special branch of geomorphology (science of the Earth's relief) which is known as morphometry. Until recently this branch was underdeveloped, although certain isolated attempts in this field were made some time ago. Currently morphometry has been receiving increasing attention, and the accumulated morphometric data already reveal, in certain cases, some patterns which facilitate the grouping of relief forms into certain categories; even an attempt to elucidate certain general causes of the development of the leading forms has been made.