Conditions of occurrence

Thickness or thickness of the layers usually remain unchanged over long distances, but there are many such cases and when it is more or less rapidly increasing or decreasing. Sometimes a layer or layer, gradually decreasing, is reduced to zero, or as they say, wedges. The above figures represent two examples of this phenomenon. The first one shows how a certain system of separate layers of strata wedge out and are replaced by other, second and third represent one of the tremendous Dolomites in South Tyrol, Seth Zass at St. Cassian. The height of this mountain of 2.559 meters, it consists of the powerful masses of dolomite, the latter refers to the upper tiers of the Triassic system and rests on the horizontal layers of so-called kassianovskogo marl. To the left stands a lower dolomitic rock, reef Richthofen. It has no connection with the main mass Seth Zass and separated from it marl. Seth Zass dolomite forms the upper layer of the latest education under him is marl and marl under the dolomite reef Richthofen, under the latter again is marl. Drawing attention to the layers of dolomite, presented on the right, we note that the power to reduce them, and finally reduced to zero. Layers, which are at relatively high power have a slight stretch and wedge out from all sides and are called lenticular. The ratio of dolomite and marl Seth Zass represented in our illustration. This is a very obvious way is not always applicable. Not every geologist has a pencil and can not always take on their expedition photographic apparatus, shooting one way or another time-consuming. Finally, often known for it is impossible to draw any conclusions about the nature of occurrence of species, for example, if the terrain is covered with rich vegetation. In such cases, resort to other ways to represent: the devil cuts or profiles. This method is widely used in geology and is as follows: this area mentally dissect the vertical plane, such an imaginary cross-section obtained on the basis of theoretical considerations based on observations and put on paper in schematic form. Need a bit of skill to handle the profiles, because in the future we will often use them, then we'll talk about this subject in more detail. When drafting the geological profiles should, if possible, to preserve the natural relationship of horizontal and vertical dimensions, the only way to get a correct idea of ??the character of the area. But this is not always feasible: if the research carried out in malokulturnoy country that has no precise topographic maps, then an idea of ??the correct spatial relationships impossible, just as a geologist is satisfied rough drawing, when you need to present the main character of the landscape on the basis of a quick and superficial research. Finally, in areas covered by low hills, changing the vertical size is very small, therefore, presenting a profile more or less large area, it is difficult to preserve the natural correct spatial relationships. For the sake of clarity, most geologists take in a vertical direction two or three times larger scale than in the horizontal direction. It must be remembered that these drawings do not correspond to reality and can easily mislead, and therefore resort to them should be only in extreme cases.