A marked feature is the absence from the map of small negative structures. This is probably explained by their masking by sediments (so that the structures were not discovered by the investigators), as well as by the fact that many negative relief forms are occupied by lakes of which only a small number were marked on the map.
Studies of the morphometric features of the structures marked on the neotectonic map of the USSR revealed considerable inaccuracies in some parts of the map. This is illustrated by the structures in northeastern Siberia, which are depicted in an overgeneralized manner, so that their contours are quite distorted from the viewpoint of the possible mechanism of their formation. Another instance is provided by the representation of the positive (uplifted) structures in Transbaikalia which are shown exces sively long on the map, whereas actually they are lenticular. These errors stand out very clearly in a comparison of the positive structures of this region with the negative structures which are depicted more correctly on the map. Moreover, the authors of the map overgeneralized the structures of Altai, Sayan, and several other regions, whereas the Tien Shan structures are depicted in a much more satisfactory manner.
Morphometric processing of the data given on the neotectonic map of the USSR achieved several purposes.
First, the basic material confirmed the patterns that were delineated in establishing the general morphometric series.
Secondly, it became possible to identify the tectonic structures of the platform and the geosynclinal regions, their graphic expression, and their morphometric features (see Figure 2).
Finally, consideration of the characteristics of well-studied structures and the patterns expressed in the form of the morphometric series made it possible to reveal the errors and inaccuracies in the map itself. This confirmed the importance of taking account of the morphometric indexes in the compilation of specialized geological, tectonic, and similar maps.
Analysis of varied and voluminous morphometric data, including those taken from the neotectonic map of the USSR, shows that the general morphometric series of relief forms and tectonic structural forms expresses numerically the general pattern that can be traced in nature and that is reflected by small and large relief forms and by tectonic struc tures of exogenous and endogenous origins.*
In this paper we shall not discuss the development of the relief forms due to external agents (wind, running water, etc.), although this aspect is important for the elucidation of all the general patterns; we shall, however, dwell on certain interesting interrelationships which became manifest during attempts to correlate the tectonic structures with the internal structure of the Earth's crust.
Obviously, any relief form or tectonic structure possesses "roots", i.e., a zone in the Earth's crust which is under the load of a positive relief form or whose deformation was involved in the formation of the form itself. Examples are seen in the interaction of engineering structures with their bed, manifesting itself in the subsidence of the ground under loads or in the decompression of structures in foundation pits. These subjects are studied in detail by geological engineers, builders, and other specialists and are beyond the scope of this paper. In the case of small structures and small relief forms the zone of their interaction with the underlying masses is usually small, but large relief forms may also possess deeper "roots".
Morphometric analysis of tectonic structures and relief forms revealed that these fall regularly into several orders; consequently their "roots" must also be arranged in certain stages in the Earth's crust and not in a random fashion. In order to test this conclusion we analyzed data on the location of earthquake hypocenters provided by several sources, including Rozova (1950) and Magnitskii (1953). Graphs based on these data (Table 7) display an remarkable similarity to our own graphs (see Figures 3, 4, and 5), suggesting a fairly pronounced relationship between tectonic structures and the internal structure of the Earth's crust.
On the basis of the patterns discerned from the general morphometric series (see Table 1), it may be assumed that most earthquakes occurring in Central Asia are related to the development of structures of the order XIII, XIV, and XV. TheseincludetheIssyk -KulandtheFerganadepressions which correspond to structures of the order XIV. Some of the earth quakes having their hypocenters at depths of 200-300 km are probably related to the development of large planetary structures of the order XVI.