Praktikum Geologi Struktur 2024 - Modul 2. Proyeksi dalam Struktur Geologi - 2. Metode Tiga Titik

Summary

This video tutorial covers the Three-Point Method in geological studies, focusing on how to determine the orientation of rock layers when field measurements are impractical. The method helps to calculate the dip and strike of geological layers by analyzing map projections, using contour lines, scale bars, and known elevation points. The video walks through the process of drawing projections and measuring angles, making it a valuable resource for geology students and professionals. It emphasizes the importance of this method in producing accurate geological maps and understanding subsurface structures, even when physical access to formations is limited.

Takeaways

• 😀 The video explains the 'Metode Tiga Titik' (Three-Point Method) used in geological structure studies to determine the orientation of rock layers.
• 😀 The method helps to determine the dip (angle) and strike (direction) of geological layers in the field using contour maps and scale bars.
• 😀 Not all geological fieldwork can involve measuring rock layers directly with a compass due to various field conditions such as erosion or unexposed layers.
• 😀 Understanding the average orientation of layers is important for creating geological maps, which need to be accurate down to every centimeter.
• 😀 The method involves identifying lithological boundaries on a map, which may be complex and wavy, as seen in the example with two lithological layers (JP and JS).
• 😀 The process involves drawing lines at the same elevation to connect the contacts between rock layers and determining the differences in elevation between them.
• 😀 The elevation difference between contacts (e.g., from 7,600 to 6,800 meters) is used to reconstruct the layer's dip, which is represented on a scale according to the map's scale bar.
• 😀 Using a scale bar, the measured distances on the map are converted into real-world distances, helping in accurate drawing and interpretation of geological features.
• 😀 By using basic tools like protractors and scale bars, you can calculate both the strike (direction) and dip (angle) of rock layers from the map data.
• 😀 The method can be applied to various field scenarios with multiple points (P1, P2, P3), and the goal is to connect these points to form an accurate representation of the geological layer's orientation.

Q & A

What is the Three-Point Method (Metode Tiga Titik) in geological structure analysis?

The Three-Point Method is a classical technique used by geologists to determine the orientation of rock layers, including calculating the dip and strike, based on three points at different elevations.

Why is the Three-Point Method important for geologists?

It is crucial because geologists cannot always measure geological features like dip and strike directly in the field due to various challenges such as weathering, obscured rock layers, or inaccessibility.

What difficulties might geologists face in the field that make the Three-Point Method necessary?

Geologists may encounter difficulties like weathered rocks, massifs that hide geological features, and other non-technical factors that prevent direct measurement of dip and strike in the field.

How is the dip calculated using the Three-Point Method?

The dip is calculated by determining the elevation differences between points on the geological map, connecting them, and measuring the angle between the horizontal plane and the plane of the geological layer.

What is the significance of using scale bars in the Three-Point Method?

Scale bars help convert map distances into real-world measurements, allowing geologists to calculate the correct dip and strike by measuring distances on the map and applying the scale to actual distances.

What is the role of contour elevation in the Three-Point Method?

Contour elevation helps determine the vertical difference between points on the geological map, which is crucial for calculating the dip and constructing the orientation of the geological layers.

In the provided example, how is the relationship between the JP and JS layers determined?

The relationship is determined by identifying the points where the JP and JS layers intersect at the same elevation, connecting those points, and then calculating the dip and strike based on their position.

What is the purpose of drawing lines between points of different elevations in the Three-Point Method?

Drawing lines between points at different elevations helps visualize the orientation of the geological layers and calculate the dip, allowing for a better understanding of the structure's geometry.

What does the strike represent in the Three-Point Method?

The strike represents the direction of the line formed by the intersection of a horizontal plane with the geological layer, typically measured in degrees from the north or south.

Can the Three-Point Method be applied to any geological feature?

Yes, the Three-Point Method can be applied to various geological features as long as there are clear contact points at different elevations, which allow for accurate determination of dip and strike.