Under heat and pressure granite can transform into :
🔥 Understanding Metamorphism
Metamorphism is the process by which an existing rock (called the parent rock) is changed into a new type of rock. This transformation happens deep within the Earth's crust due to intense heat and pressure, without the rock melting completely. The minerals within the parent rock recrystallize and realign to form a new metamorphic rock.
🔬 Detailed Analysis of the Options
C. Gneiss
This is the correct answer. When granite (an igneous rock) is subjected to high-grade metamorphism (very high heat and pressure), its mineral components—quartz, feldspar, and mica—realign themselves. They segregate into distinct light and dark bands, creating the characteristic foliated (banded) texture of Gneiss (pronounced "nice").
A. Marble
Marble is a metamorphic rock, but its parent rock is Limestone or Dolostone (sedimentary rocks). Heat and pressure cause the calcite in the limestone to recrystallize into a denser, sparkling rock.
B. Slate
Slate is a low-grade metamorphic rock known for its ability to split into thin sheets. Its parent rock is Shale (a sedimentary rock made of clay).
D. Quartzite
Quartzite is a very hard metamorphic rock. Its parent rock is quartz-rich Sandstone (a sedimentary rock). The heat and pressure fuse the quartz sand grains together into a solid mass.
📊 Summary: Parent Rocks and Their Metamorphic Forms
| Parent Rock | Rock Type | Metamorphic Rock |
|---|---|---|
| Granite | Igneous | Gneiss |
| Limestone | Sedimentary | Marble |
| Shale | Sedimentary | Slate |
| Sandstone | Sedimentary | Quartzite |
💡 Study Tips
- Granite is "Gneiss": This is a classic association to remember. Granite looks "nice," and it turns into "Gneiss."
- Limestone to Marble: Think of the Lincoln Memorial, made of marble that came from limestone.
- Sandstone to Quartzite: Both have "sand" or "quartz" in their names, making the link easy.
- Shale to Slate: Both are fine-grained and can be associated with layers or sheets.