The wedging is adopted for quarrying costly stratified rock such as
⛏️ Understanding Quarrying by Wedging
Wedging is a method used to split rock from its bed without using explosives. It's a much gentler technique, ideal for extracting large, intact blocks of valuable stone.
The process involves:
- Drilling a series of holes along the desired line of fracture.
- Placing steel wedges and shims (also called "plugs and feathers") into the holes.
- Tapping the wedges sequentially with a sledgehammer, creating immense outward pressure that splits the rock cleanly along the line of the holes.
This method is preferred for costly stones because it prevents the micro-fractures and waste associated with blasting.
🔬 Detailed Analysis of Rock Types
The key to this question is understanding which rocks are both "costly" and "stratified." Stratified rocks are those formed in layers, which have natural planes of weakness that make them easy to split. This includes most sedimentary rocks and some metamorphic rocks.
E. All the above
This is the correct answer. The wedging technique is versatile and can be used on any rock that has natural bedding planes or lines of weakness (foliation) and is valuable enough to justify the careful labor involved.
A. Laterite
Laterite is a stratified rock formed in tropical regions. When used as a building material, it is cut into blocks. Wedging is a perfectly suitable method for extracting these blocks.
B. Marble
Marble is a costly metamorphic rock. It doesn't have strata in the same way as sedimentary rocks, but it does have planes of weakness from its formation (foliation). To get large, perfect slabs for decoration, wedging is an ideal, non-destructive method.
C. Limestone & D. Sandstone
Both limestone and sandstone are classic examples of stratified sedimentary rocks. Many varieties are considered valuable building stones. Their natural layered structure makes them prime candidates for quarrying by wedging.
📊 Summary: Suitability of Rocks for Wedging
| Rock | Type | Reason for Wedging |
|---|---|---|
| Laterite | Sedimentary | Stratified; cut into blocks. |
| Marble | Metamorphic | Costly; has planes of weakness (foliation). |
| Limestone | Sedimentary | Costly; clearly stratified. |
| Sandstone | Sedimentary | Costly; clearly stratified. |
💡 Study Tips
- Wedging = Gentle Splitting: Think of wedging as a gentle way to split things, like using a wedge to split a log. You do this for valuable material you don't want to shatter.
- Stratified = Layered: Any rock with layers (strata) or planes of weakness is a good candidate for wedging.
- Costly + Layered = Wedging: If a rock is both valuable and has layers, wedging is the go-to method. Since all the options can fit this description, "All the above" is the logical choice.