How to use a compass?

1. How to use the compass

1. The structure of the compass

(1) Magnetic needle - generally a rhombus-shaped steel needle with a wide middle and sharp points on both sides. It is installed on the thimble in the center of the chassis and can rotate freely. When not in use, the brake screw should be tightened, and the magnetic needle should be lifted and pressed against the cover glass to avoid collision between the magnetic needle cap and the needle tip, so as to protect the thimble tip and prolong the use time of the compass. When measuring, loosen the fixing screw to allow the magnetic needle to swing freely. When finally stationary, the magnetic needle points in the direction of the magnetic needle meridian. Because our country is located in the northern hemisphere, the magnetic forces at both ends of the magnetic needle are unequal, causing the magnetic needle to lose its balance. In order to keep the magnetic needle balanced, several turns of copper wire are often wound around the southern end of the magnetic needle. This can also be used to distinguish the north and south ends of the magnetic needle.

(2) Horizontal dial---The scale of the horizontal dial is marked in this way: starting from zero degrees, mark every 10 degrees in the counterclockwise direction, and continue to mark 360 degrees, o degrees and 180 degrees are N and S respectively, 90 degrees and 270 degrees are E and W respectively. It can be used to directly measure the magnetic azimuth angle of a straight line between two points on the ground.

(3) Vertical dial——Specially used to read inclination and slope angle readings, with E or W position as 0 degrees, S or N as 90 degrees, and corresponding marks every 10 degrees number.

(4) Suspension cone---is an important part of the inclinometer. It is suspended below the axis of the magnetic needle. The suspension cone can be rotated through the target wrench at the chassis. The tip in the center of the suspension cone is Refers to the scale as the degree of inclination or slope angle.

(5) Level---There are usually two, each installed in a circular glass tube. The circular level is fixed on the chassis, and the elongated level is fixed on the inclinometer.

(6) Sight - including an object-receiving and target-receiving plate. There is a thin line in the middle of the reflector and a transparent hole in the lower part, so that the eye, the thin line, and the target are in line. For aiming purposes.

The magnetic declination must be corrected before use.

Because the geomagnetic south and north poles do not exactly match the geographical north and south poles, that is, the magnetic meridian does not coincide with the geographical meridian, and the magnetic north direction of any point on the earth is inconsistent with the true north direction of that point. The angle between these two directions is called magnetic declination.

If the northern end of the magnetic needle at a certain point on the earth is tilted to the east of due north, it is called easterly, and if it is tilted to the west, it is called westward. East deviation is (+) and west deviation is (-).

The magnetic declination angles of various places on the earth are calculated regularly and published for reference. If the magnetic declination angle at a certain point is known, the relationship between the magnetic azimuth angle A of a survey line and the true north azimuth angle A is A equal to A plus or minus the magnetic declination. This principle can be used to correct the magnetic declination. When correcting, the compass scale spiral can be rotated to rotate the horizontal dial to the left or right (the magnetic declination moves to the right when it moves to the east, and to the left when it moves to the west). , so that the angle between the north and south scale lines of the compass chassis and the line connecting 0--180 degrees on the horizontal scale is equal to the magnetic declination. After correction, the measurement reading is the true azimuth angle.

2. How to use a compass

(1) Measuring the orientation

Measuring the orientation of an object is the most basic skill that field geologists should possess. When fixing a point, the first thing to do is to measure the orientation of the observation point on a certain terrain or feature. When measuring, open the compass cover, loosen the brake screw, and allow the magnetic needle to rotate freely. When the object to be measured is tall, put the compass on your chest, aim the long level of the compass at the object to be measured, and then rotate the reflector so that the object and the long sight are reflected in the reflector, and aim the object and the long sight. The tip of the short sight on the instrument and the center line of the reflector are in a straight line, while keeping the compass level (the bubble of the circular level is centered). When the magnetic needle stops swinging, you can directly read the value on the circular dial pointed by the magnetic needle. You can also press the brake screw to read again.

(2) Measure the rock formation occurrence factors

The rock formation occurrence factors include the direction, tendency and inclination of the rock formation. The trend of the rock formation is the extension direction of the intersection of the rock formation layer and the horizontal plane. The dip of a rock layer is the direction of the projection of the inclined line on the rock layer onto the horizontal plane. The inclination angle is the angle between the inclined line and the horizontal plane.

When measuring the direction of the rock formation, place one edge of the long side of the compass (parallel to the side marked N-S on the compass) close to the layer, as shown in the picture, and then slowly rotate the compass (note: in During the rotation process, no point on the edge of the compass close to the layer can leave the layer), so that the bubble of the circular level is centered and the magnetic needle stops swinging. At this time, the reading pointed by the magnetic needle is the direction of the rock formation. You can read either the magnetic north needle or the magnetic south needle because the rock formations extend in both directions, 180° apart.

When measuring the inclination of the rock formation, place the compass as shown in the figure. Place the edge of the south end of the compass (marked S) close to the rock layer. At this time, the long sight points in line with the inclination of the rock formation, and rotate the compass. The methods and principles are the same as above. When the compass is level and the magnetic needle does not move, readings can be taken. Place the compass as shown in Figure 1 and read where the magnetic north needle is pointing. After measuring the inclination, do not let the compass leave the rock layer. Immediately turn the compass 90° (the compass is upright). Place it as shown in Figure 1 so that the long side of the compass is close to the rock layer and coincides with the tilt line. Then rotate the bottom of the compass. Use the handle to center the bubble of the level (long level) on the inclinometer. At this time, the reading on the semicircular dial pointed by the cursor on the inclinometer is the inclination angle.

When measuring the occurrence of strata, it is generally only necessary to measure the inclination and inclination of the formation, and the direction can be obtained by adding or subtracting 90° from the inclination number. When measuring the inclination and inclination, the inclination must be measured first and then measured. inclination.

If the surface of the rock layer being measured is uneven, the record book can be placed flat on the rock layer as a layer to improve the accuracy and representativeness of the measurement. If the rock formation is very incompletely exposed, you need to find the section of the rock formation and find three points belonging to the same layer (usually easy to find in two intersecting sections), and then use a record book to connect these three points into a plane ( Equivalent to the rock layer), then just measure the plane of the record book.

2. Field geological records

1. Field geological record requirements

Detailed records: When conducting field geological observations, records must be kept. Geological records are the most valuable The original data are the basis for comprehensive analysis and progressive research, and are also one of the manifestations of the results of geological work. Objectively reflect the actual situation: that is, remember what you see and reflect it truthfully. You cannot exaggerate, reduce or distort it subjectively. However, the author's analysis and judgment of geological phenomena are allowed to be expressed in the records. Because this helps to improve the predictability of observation and promotes a deeper understanding of the problem. The record is clear, beautiful, and the writing is clear: This is a criterion for measuring the quality of the record. Pictures and text: Pictures are an important means of expressing current geological phenomena. Many phenomena are difficult to explain clearly using words alone and must be supplemented by illustrations. In particular, some important geological phenomena include the structure, structure, faults, folds, joints and other structural deformation characteristics of primary sediments, the primary structures, strata, rock masses of igneous rocks and their mutual contact relationships, mineralization characteristics, and other internal, External dynamic geological phenomena should be represented by drawings as much as possible. The value of good drawings far exceeds mere written records.

2. Contents of field geological records

The recording of comprehensive geological observations must be comprehensive and systematic. For example, for regional geological surveying and mapping, a recording method that combines observation points and observation lines is often used. . Observation points are geologically relevant, representative and characteristic locations. Such as changes in strata, structural contact lines, locations of rock masses and mineralization, and other important geological phenomena. An observation line is a continuous route connecting observation points, that is, observing along the way to achieve the purpose of connecting the situations between observation points. The specific record contents of observation points and observation lines are as follows:

Date and weather. The place name of the internship area. Route: where you pass and where you go, you should write it clearly and clearly. Observation point number: starting from No.01, No.02, No.03,…. Location of the observation point: Be as detailed as possible, such as which mountain, which village, which direction, how many meters away, whether it is next to the avenue or the road, on the hillside or in the valley, on the concave bank of the valley or in the valley. For convex banks, etc., the elevation of the observation point must also be recorded, that is, the altitude, which can be interpreted based on the topographic map. The location of observation points should be determined and marked on the corresponding topographic map. Purpose of observation: Explain what the object of observation is focused on at this observation point, such as observing the strata and contact relationships of a certain era, observing certain structural phenomena (such as faults, folds...), observing the characteristics of igneous rocks, observing certain external forces Geological phenomena, etc. Observation content: Record the observed phenomena in detail, which is the essential part of the observation record. The focus of observation is different, and accordingly there are different recording contents. If the observation object is a layered geological body, it can be recorded according to the following procedures.

① Rock name, lithological characteristics, including rock color, mineral composition, structure, structure and engineering characteristics;

② Fossil situation, whether there are fossils and how many fossils there are, Preservation status, fossil names;

③ Determination of the age of rock layers;

④ Vertical changes of rock layers, contact relationships between adjacent strata, list evidence;

< p>⑤The occurrence of rock formations is recorded in the azimuth format;

⑥The fold status of the exposed rock formations, the judgment of the structural location of the rock formations, whether it is the wings or the axis of the folds, etc.;

p>

⑦The development status of small joints in the rock layer, the nature and density of the joints, the occurrence of the joints, especially the direction of the joint extension; whether the rock layer is broken or not, the degree of breakage, the existence of faults and their nature, evidence, Fault occurrence, etc.;

⑧Geomorphology, Quaternary system (mountains, terraces, meanders, etc.), longitudinal and transverse sections of river valleys, valley terraces and their properties, hydrology, hydrogeological characteristics and physical geological phenomena ( Such as the distribution of karsts, landslides, gullies, collapses, formation conditions and development rules, and the impact on engineering construction, etc.);

⑨The number of the specimen, such as the specimens, samples or photography taken, etc. , should be marked accordingly;

⑩Supplementary records. Phenomena not yet covered by the above.

If the observation point is an intrusive body, except for fossils, which are not recorded, other items should have corresponding content. For example, item 4 should be intrusive contact relationship or sedimentary contact relationship; item 5 should be rock mass. , be rock dikes, rock walls, rock beds, rock strains or rock foundations; item 6 should be whether the structural part of the rock mass intrusion is the fold axis or wing, whether it is intruded along a fault or some kind of rupture surface, etc. The above-mentioned record content is comprehensive, but in actual application, it should be emphasized according to the nature of the observation point.

Observe and record various geological phenomena between adjacent observation points along the way to connect the relationships between points.

Draw various sketches and cross-sections, usually recorded on the right page of the record book and drawn on the left page. Route summary, briefly explaining the main results of the day's work, and any remaining doubts or points that should be paid attention to.

The above record items should be separated one by one. Except for the date and weather in the same cell, all other items should be opened in new lines

3. Draw a schematic diagram of stratigraphic profile

p>

1. Contents of the stratigraphic section schematic diagram

The stratigraphic section schematic diagram is a schematic diagram that represents the actual situation of stratigraphic exposure in the field. Used in route geological work. It further reflects the occurrence, layering, lithology, fossil production location, stratigraphic thickness, contact relationship and other stratigraphic characteristics of a certain or certain strata on a section that outlines the terrain.

The topographic profile and thickness of stratigraphic layers in the schematic stratigraphic profile diagram are visual estimates rather than actual measurements. This is the main difference between it and the measured stratigraphic profile.

2. Drawing steps

Determine the section direction, which is generally required to be perpendicular to the stratigraphic trend line. The scale is selected so that the drawn section is not too long or too short, and at the same time meets the needs of representing each layer. If the actual profile is long and the stratigraphic layering content is numerous and complex, the profile should be longer; otherwise, the profile should be shorter. Generally speaking, try to keep a picture within the length of the record book, which is more convenient for drawing and reading. If the actual section length is 30m and the layer thickness is several meters or more, a scale of 1:200 or 1:300 can be used for drawing. Draw the terrain outline according to the selected section direction and scale, and the terrain's ups and downs must conform to the actual situation. Draw the boundaries of the strata and their layers with a straight line below the corresponding point of the terrain profile according to the true dip angle value of the stratum. At this time, the true thickness of each layer and its layers can be measured from the map. Pay attention to check the map. Whether the thickness reflected is consistent with the actual thickness estimated by visual inspection. If not, the problem in the drawing must be found and corrected. Various common patterns and codes are used to indicate the lithology, contact relationship and age of each stratum and layer, and to mark the fossil production location and stratigraphic occurrence. Mark the title, legend, scale, direction, and names of features on the section map.

4. Draw the Xinshou geological profile

If comprehensive geological observation is carried out across the direction of the structural line, the Xinshou geological profile should be drawn, which represents the geological profile across the structural line. Structures below the earth's surface. This is a comprehensive map that not only represents strata, but also structures, igneous rocks and other geological phenomena, as well as terrain relief, names of features, and other comprehensive information that needs to be represented. Sexual content. Drawing a good route geological profile is an important basic skill for geologists and must be mastered.

The terrain relief contours in the Xinshou geological profile of the route are estimated visually, but they must basically reflect the actual situation. The relative distances between various geological bodies are also visually estimated and should be basically correct. The occurrence is actually measured, so when drawing, you should strive to be accurate.

The content on the map should include the map title, section direction, scale (generally the horizontal scale and vertical scale are required to be consistent), terrain outline, stratigraphic sequence, location, code, occurrence, rock mass symbol, Rock mass exposure location, lithology and code, fault location, nature, occurrence, and feature names.

The specific drawing steps are as follows:

Estimate the total length of the route, select the scale of the drawing, and try to control the length of the profile within the length of the record book. Of course, if the route is long, The geological content is complex and the section can be drawn longer. Draw a terrain profile, visually estimate the horizontal distance and height difference of terrain turning points, and accurately determine the slope and size of the hillside. A common mistake for beginners is to draw the hillside steeply. Generally, the slope does not exceed 30°, and steeper slopes are difficult for people to pass smoothly. At the corresponding points of the terrain profile, draw the position, inclination and inclination of the interfaces and fault planes according to the measured layer and fault plane occurrences, and draw the position and shape of the rock mass at the corresponding parts. Corresponding layers are connected by lines to reflect the presence of folds and cross-sectional characteristics. Mark the strata, lithological patterns of rock masses, the movement of faults, codes of strata and rock masses, fossil origins, sampling locations, etc. Write down the map title, scale, section direction, feature names, drawing legend symbols and descriptions. If it is a customary legend, it can be omitted

In terms of drawing skills, you should pay attention to the following three "Accurate": ① The topographic profile must be drawn accurately; ② The positions of marker layers and important geological boundaries must be drawn accurately. Such as the location of faults, coal-bearing strata, igneous rock bodies, etc.; ③ The occurrence of rock formations must be accurately drawn, especially the inclination cannot be reversed, and the inclination angle must conform to the actual situation. In addition, the line pattern should be meticulous, uniform and beautiful, the fonts should be neat, and the layout of various notes should be reasonable.

5. Drawing field geological sketches

Geological sketches are paintings that use perspective principles and painting techniques to express geological phenomena or geological processes from a geological point of view. Geological sketches drawn in the field are usually carried out during the process of investigation and observation, and are often required to be completed in a short period of time. They are usually drawn with pencils or pens in their own field notebooks. It is impossible to do it with precision, so it is also called "geological sketching". Geological Sketch Sketch.”

1. Advantages of geological sketching

Geological sketching has many advantages over geological photography.

In addition to the advantages of geological sketching, which is not limited by weather, lens viewing range, close-up and distant views, and is more economical, more importantly, when we analyze a certain geological phenomenon, we think which features should be emphasized, which appendages or nearby vegetation are important to When these features are interfering and should be eliminated, if we use photography to faithfully reproduce the objective scenery, the priority will be ignored, the geological content will not be highlighted, and the desired effect will not be achieved. If you use sketching technology, you can completely choose the characteristics of various geological phenomena and nearby scenery according to the needs of the observer. Which ones should be highlighted and which ones should be simplified can be described and reflected by one's own pen. Facts have shown that if a geological survey report can make full use of geological sketches, it will not only help to reveal and explain the nature of the problem, but also avoid unnecessary text descriptions, making it concise and to the point, with both text and pictures, and the effect will be better

2. Basic steps of geological sketch

Select the range of the sketch object and determine the position of the scene within the frame. Arrange the size ratio and relative position of the main and secondary objects, and outline their scope within the frame. Draw the outline of a scene (or geological body). The main thing is to grasp the contours, such as ridges, cliffs, river beds, terraces, levels, faults, etc. When sketching, draw near first and then far away. The near areas should be detailed, clear, and dense, while the far areas should be drawn roughly, lightly, and vaguely. Try to apply the pen in accordance with the principle of perspective. After the outline is ready, add hatching. This step is mainly to master the three-dimensional sense of the scene image and make it realistic. Appropriately draw some background or foil to beautify the picture. In order to clearly express the content of the picture, necessary text can be marked near the scenery (or geological body), such as villages, stratigraphic age symbols or other symbols, etc. Finally, write the map title, place name, orientation, measurement data, scale and other necessary instructions.

3. Types of geological sketches

According to their content, the most common types of geological sketches are as follows:

Stratigraphic sketches. The sketch object is the stratum, which represents the stratigraphic layer relationship, stratigraphic characteristics, etc., such as stratigraphic section sketch. Geological structure sketch. The main objects are folds, faults, joints and other structural geological phenomena. Pay attention to these places respectively when sketching them.

Fold sketch: Before starting the sketch, you should first consider which layer can be used as the "marker layer" and the lithological characteristics of this "marker layer" and how to express the sketching techniques. When sketching, you can focus on the "marker layer" to fully display the fold shape.

Fault sketch: Just like folds, you should first find out its "marker layer" to judge the relative movement of the two fault plates and determine the fault type.

Joint sketch: When sketching, several groups of joints in different directions should be clearly expressed. Pay attention to the intersection angle between each group and the width of each group of joints in line with reality and the principle of perspective.

Landform sketch. Geomorphic sketch is a type of sketch with a broad vision. From a geological perspective, it mainly expresses the relationship between landform features, rock properties and geological structures, or the relationship between weathering, water erosion, glaciers, volcanoes, earthquakes and other geological processes and landforms.

Typical geological phenomena seen in the wild are as small as a specimen or a primary sedimentary structure on an outcrop, secondary structural deformation (faults and folds), and erosion and weathering; as large as The geological structural characteristics or internal and external dynamic geological phenomena (such as ice erosion terrain, valley terraces, volcanic crater landforms) within a mountain top or even many mountain tops can be represented by geological sketch maps. A sketch is a painting, and its principle is the same as that of painting. However, a geological sketch must consider the geological content and reflect the characteristics of the geological structure.

Geological sketching is similar to photography, but photography is a purely intuitive reflection, while geological sketching can highlight the key points of geological content, and the author can make choices. Photography requires conditions, but geological sketching can be done at any time. Therefore, geologists should learn the method of geological sketching as a means of conducting geological surveys

6. Collection of specimens

The process of field geological work is the process of collecting geological data. Geological data In addition to written records and various drawings, specimens are indispensable practical data. With various specimens, further analysis and research can be done indoors to deepen the understanding. Therefore, care must be taken when collecting specimens in the wild.

According to the purpose, the specimens are divided into stratigraphic specimens, rock specimens, fossil specimens, ore specimens, and specimens for special purposes (thin section identification, isotope age determination, spectral analysis, chemical analysis, structural orientation, etc.).

Specimens should be fresh and not weathered.

Stratigraphic specimens and rock specimens are commonly used. There are requirements for the size and shape of such specimens. They are generally rectangular in shape, and their specifications are 3cm × 6cm × 9cm. It should be collected, processed and modified at artificial mining sites such as quarries and mines or on favorable natural outcrops. Fossil specimens strive to be complete. Ore specimens are required to reflect the characteristics of the ore. For thin section identification, chemical analysis, spectral analysis and other items, the shape of the specimens is not required, but freshness is required, and an appropriate quantity is sufficient.

After the specimens are collected, they should be numbered immediately and written on the corners of the specimens with paint or other substitutes to prevent them from being rubbed off.

At the same time, mark the specimen collection location and number with corresponding symbols on the cross-section or plan view, register it in the specimen registration book, fill in the label and package it. Fossil specimens, in particular, must be carefully packed with cotton to avoid damage.

7. Measured geological profile

In order to study the stratigraphic lithology, geological structure and engineering geological conditions of the hydraulic construction site in the work area, it is necessary to measure the geological profile. The specific method steps are as follows.

1. Arrange section lines

In order to correctly understand the stratigraphic sequence in the work area and find out the lithology combination, thickness, marker layer and contact relationship of the strata of each era, we often choose In areas with good rock outcrops, clear sequences, simple structures, representative or typical significance, lines are arranged to make measured geological sections. The direction of the section line should be as perpendicular to the trend of the rock strata or perpendicular to the direction of the main structural lines as possible. At the same time, the section line should also consider making full use of natural outcrops and artificial outcrops. In order to reflect the engineering geological conditions of relevant projects such as dams, powerhouses, tunnels, spillways, and channels, measured geological profiles can be made along the project axis or cross-sectional direction.

2. Select the scale

The selection of the section scale should be based on the specifications and the requirements of the measured object, and should be based on the principle of fully reflecting the smallest stratigraphic unit or lithological unit. The commonly used scale is 1:500~1:5000. For rock formations with special significance (such as landmark formations) that are less than 1 mm in the cross-section, they can be appropriately enlarged and shown, but their actual thickness should be noted in the record.

3. Arrange measuring points

Measuring points should be arranged along the profile line and should be selected in places with changes in topographic and geological conditions. The spacing should be determined according to the accuracy requirements of the scale. For example, when making a 1:500 measured profile, the distance between measuring points should be less than 5m. If the terrain is undulating or the geological conditions are complex, the distance between measuring points should be appropriately reduced. Each measuring point must be marked and numbered uniformly.

4. Profile topography measurement

Profile topography measurement usually uses the semi-instrument method wire measurement, that is, using a geological compass to measure the direction of the wire and the terrain slope angle section by section, and using a tape measure or measuring tape. The rope measures the slope distance of the ground. For large-scale measured profiles, theodolite should be used to measure the position and elevation of each point.

5. Observation and recording of geological conditions

While conducting profile topographic measurements, collect geological data. Its observation records include stratigraphic layers, rock names, lithological characteristics, rock formation occurrences, fracture structures, weathering conditions, composition and thickness of Quaternary accumulation layers, groundwater outcrops and natural geological phenomena, etc., and the necessary rock formations are collected. Sample.

6. Draw a profile map

After carefully reviewing the terrain and geological data measured in the field and confirming that they are correct, prepare a measured geological profile map according to the requirements of the geological profile diagram.

Draw a plan view of the conductor: According to the orientation and horizontal distance of the conductor, draw the conductor point by point from the base point (starting point) to the end point according to the scale, and divide the rock layers 8. Measurement and statistics of joints

< p>1. Measurement of joints

The measurement and description of joints are shown in Table 1.

Table 1 Joint field measurement record number Rock name and occurrence elements Joint occurrence Cause of joint (mechanical properties) Joint width, length, and description of joint surface Filling material and cementation degree in joints Other trend trends Inclination For statistical purposes, the size of the measurement area depends on the density of the joints. Generally speaking, if 50 to 60 occurrences can be measured in a group of joints, it will have good statistical effect.

2. Compilation of joint rose diagram

Take the preparation of the most common "moving rose diagram" as an example. First, organize the data. Convert all the joint directions measured at the measuring points into NE and NW directions, group them according to the direction and direction, using 10° as an interval, and divide them into 1°~10°, 11°~20°,..., and count each group of joints Number of bars and calculate the average trend.

Secondly, determine the scale of the drawing. According to the drawing size and the number of joints in the group with the largest number, a line segment of a certain length is selected as the line scale of a joint, and then the length of the line segment that is equal to or slightly longer than the line scale representing the number of joints in the group with the largest number is used as the radius. Draw an upper semicircle, draw three directions E, W, and N through the center of the circle, and mark the azimuth angle.

Again, connect fixed points. Starting from the first group of 1° to 10°, find the point corresponding to the middle value of the azimuth angle according to the ratio of the number of joints in the group in the radial direction. This point represents the average direction and number of joints in the group. After the points of each group are determined, connect the points of adjacent groups with polylines in turn. When one of the groups has no joints, the connecting line should be folded back to the center of the circle, and then connected from the center of the circle to the points of the next group (it is best to connect the lines while finding the points).

Finally, write the title of the picture and mark the scale of the line segment. If necessary, draw the direction of the river and the orientation of major buildings (such as dam axis, etc.) to analyze and evaluate the impact of joints on hydraulic structures. Lines, occurrences and other observation points are plotted at the corresponding positions one by one to form a two-dimensional route map.

Select the section orientation: Generally, choose the direction consistent with the rock formation inclination as the section direction, or connect the starting point and end point of the baseline as the section line.

Project the profile terrain contour line: Below the conductor plan, draw a baseline of equal length parallel to the profile line, set up an elevation scale at both ends of the baseline (if the elevation of the base point is unknown, it can be calculated based on the relative height difference), and Set the left end as the starting point, then project each wire point on the accumulated height difference above the baseline, and connect the points to obtain the profile terrain contour line. Project the geological content in the profile: project the boundary points of each rock layer, various geological structures and geological phenomena on the conductor onto the terrain line, and represent the strata according to their occurrence and prescribed legend symbols (if the direction of the profile is perpendicular to the trend of the rock strata, Expressed by true dip angle, otherwise expressed by apparent dip angle) lithology and other geological conditions.