geologic section[¦jē·ə¦läj·ik ′sek·shən]
(also geologic profile), a vertical section of the earth’s crust from its surface to a depth. Geologic sections are made on the basis of geologic maps and data from geologic observations, mine works, boreholes, geophysical investigations, and so on. They are usually made at right angles to the geologic structures along straight or broken lines, which in cases of deep test holes pass through these boreholes and show the location, age, and composition of the rocks. Geologic sections are particularly important for regions covered with thick mantles of Anthropogenic accumulations. The scale line of a geologic section usually corresponds to the scale of the corresponding geologic map. The scale of height is equal to the scale line, which makes it possible to give an undistorted representation of the nature of the relief and geologic structure. The relationship between the different elements of the relief of a region and its geologic structure must be clarified when resolving many practical problems (when planning railroad lines, surveying during building construction, building dams, and so on). In such cases it is necessary to use an enlarged scale of height that exceeds the scale line by tens and even hundreds of times.
A. E. MIKHAILOV