How To Draw A Cross Section Geology
Introduction
Geological map reflects the geographical patterns of rocks and minerals components on the earth surface by ways of lithology, structure, succession of beds formation. To properly sympathize it, drawing of cross-section & interpretation of geological maps is of utmost necessity. Earlier drawing cross-sections & interpretation geological maps, we firstly proceed to read the map.
If we desire to read a geological map nosotros must have knowledge about the basic terminology. I had already discussed it in my previous article. The link to the commodity is in the box below.
Cartoon of cross-department:
On the footing of the reading knowledge of a geological map, we select the department line of the map and steep forward to drawing of the cantankerous-department. The cross-section of a geological map exposed all inner formations of stone beds. It also helps u.s.a. to translate the total geology of the map. I clearly discussed the process of the cross-section of different types of geological maps in my YouTube videos. There are unproblematic series, double series, triple series, and peculiarly annotated map with broadly elaborated their cross-section in my video classes. All the links are given below.
| Topic | Link |
| Introduction of Geological Map with Basic Terminology Part -i | Meet the video |
| Drawing of Cantankerous contour of Geological Map. Part -three (Triple & particularly annotated map) | See the video |
YouTube videos on Geological Map
Steps for drawing of geological cross-section:
one. Selection of a Department Line
2. Identification of Structure and series of the map
(Demarcation of Line of Unconformity in multi-series)
three. Cartoon of Strike line
4. Observation of Dip, Dip direction & thickness of the beds
five. Rough Sketches & interpretation for drawing of Cross Section
6. Making of the paper strip
vii. Cartoon of Cross Section
- Relief Profile cartoon
- Beds and unconformity drawing
- The sequence of beds and note
- Succession of beds Heading & Caging
- Scale of cartoon
X important geological maps with geological cross-department:
ane. Unmarried Series Maps
Geological Map No:1
Geological Map No:2
Geological Map No:3
2. Double series map
Geological Map No:4
Geological Map No:v
Geological Map No:half-dozen
Here vertical igneous body below the upper series is a dike.
Geological Map No:7
Geological Map No:8
Here vertical igneous body in both series is a dike.
Triple series and spacially annotated map
Geological Map No:9 with sample complete interpretation
Interpretation of Geological Map
In the topic drawing of cross-section and interpretation of geological maps we will now continue for interpretation of the map. The interpretation of the geological map is the outcome of its dissimilar attributes in particular. It is the final office of a geological map understanding. After drawing of cantankerous-section we generally go on for interpretation of the geological map. A sample format of geological map interpretation for map number 9, we can discuss in the following subheadings.
1. Introduction:
- Map No: ix
- The scale of the map: 1inch to 1000ft.
- Area of the map: 8inch ten 10 inch =lxxx sq. inch in the map is equivalent of 0.0199 sq miles in the ground.
- Maximum & minimum altitude of the map: 1100ft in western part & 400ft in the southern office.
- Cantankerous-department line and its length and direction: AB. A is in the western stop and B is in the eastern end. The length of AB is ten.5 inch which is about 0.166 miles in the basis.
- The number of series of the given map: It is a triple series map with two distinct unconformities.
ii. Topography:
The geological map is a part of the dissected plateau region or dissected high land region. The highest acme of the entire region is 1100ft at the western role of the map. We come across the next highest elevated about half circled flat-topped region in the northern part which is encircled by the contour 1000 ft. The lowest altitude of the region is in the southernmost part of the region where 400ft contour passes.
Therefore the relative relief of the region is 700ft. In that location are 5 river valleys in the mapped region. The principal river flows from north-northeast to south. The river dissects the upper series stone beds in the northern office and upper with lower series in centre to southward part. Two almost parallel tributaries join to the left bank of the main river from the eastern region. There is a probability of river capture found in the north-eastern part of the map. Hither ii opposite-direction-flowing rivers will meet soon with each other by their headword erosion. From the western region, other tributaries join the river on its right bank. In the middle to the s portion of the region lower series stone beds exposed by the down river erosion
3. Succession of rock beds:
I clearly represent the succession of eight rock beds and three series in the following tabular array in detail. It volition be helpful to a proper understanding of the map.
D. Geological Structure :
There are three series of stone beds in the map. The upper serial is horizontal in structure. It is equanimous of ii rock beds South & T. The thickness of the rock cannot be measurable from the map due to its horizontal manner but it can be measure from the cross-department. Both the stone beds are the aforementioned thickness. It is 100 ft each.
The center series is Uniclinal in structure. In section line AB, information technology shows an apparent dip of about 2 degrees. The heart serial is composed of two rock beds O & P. The thickness of the O bed is 100 ft and the thickness of the P bed is non measurable due to the absenteeism of its upper bedding plane.
The lower serial is folded in construction. There is a prominent anticline in the centre of the region and a syncline on the eastern side of the region. Therefore the unabridged region is consisting of three folded limbs with their different dip and direction at lower series rock beds. The lower series is composed of D, E, F & G beds where D is the oldest lower bed, and Yard is the top bed in this series. The thicknesses of the beds are 200 ft and 300 ft for E & F respectably, whereas the thicknesses of D & G beds cannot be measured due to the absenteeism of lower and upper bedding planes for D and G beds respectably.
E. The relation between Structure and topography:
At that place is a shut interrelationship between the structure and topography of the given geological map. There are five major valleys in the mapped surface area that creates a positive and negative relation between construction and topography. In the heart part of the region, the altitude is low due to the high level of erosion which makes positive relation and in the north-eastern and s-western regions, the relation is negative due to the low level of erosion. In the said both sides of the region, a steep escarpment and cap rock are formed in the horizontal structure of 'P' bed.
In the middle part of the region, a folded anticline structure is prominent in the lower series of rock beds, where the main river creates a wide and steep valley past gradual valley deepening and valley widening process. Hence the topographic expression hither is an Anticlinal valley. The oldest stone bed 'D' is exposed hither.
In the n- west office of the region the folded lower series rock beds create a syncline on which cap rock 'O' of the center series is located. Hence the topographic expression here is a synclinal ridge. And so in compare with these 2 parts we can easily translate the region is a platonic example of inversion of relief. The total region is a dissected highland with Questa, Escarpment, Mesa, and Butte topographic expression.
F. Geological History:
In the early unknown geological fourth dimension the entire region was under the sea beds where the rock beds D, Eastward, F, and G were formed in horizontal mode. At the time of uplift due to the tectonic movement, the rock beds were folded. Afterwards a long time the region were submerged over again and middle series rock beds 'O' and 'P' formed in horizontal fashion. The region were uplifted with tilting and that is why 'O' & 'P' rock beds slightly tilt towards the east disrupting their previous horizontal structure. The region was exposed to nature and later on a long menses the entire region submerged under the sea. The rock beds 'South' and 'T' were formed in horizontal style. The total region is uplifted and exposed to nature for erosion and degradation. The present relief is the issue of intensive fluvial erosion for a long fourth dimension.
Geological Map No:ten
The succession of stone beds in Geological Map No:10 for drawing and interpretation clue
And so this is the Cartoon of Cross Department And Interpretation of Geological Maps.
Source: https://theqgeo.com/drawing-of-cross-section-and-interpretation-of-geological-maps/
Posted by: littletonhiming62.blogspot.com
0 Response to "How To Draw A Cross Section Geology"
Post a Comment