The Rock formed through accumulation of volcanic ash is called:

Question

Accepted Answer

The Rock formed through accumulation of volcanic ash is called:

**Explanation:**

Option 3, **Tuff**, is the correct answer because tuff is a type of rock specifically formed from the consolidation of volcanic ash and other pyroclastic materials ejected during volcanic eruptions. Volcanic ash, being fine-grained, settles and compacts over time, often with the aid of heat and pressure, to form tuff. The composition of tuff can vary depending on the source volcano and the type of eruption, but its defining characteristic is its origin from accumulated volcanic ash.

Now, let's explain why the other options are incorrect:

*   **Option 1, Sill:** A sill is an intrusive igneous rock formation. It's formed when magma intrudes between existing layers of rock and solidifies. It's not formed from the accumulation of volcanic ash on the surface.

*   **Option 2, Scoria:** Scoria is a vesicular (full of holes) volcanic rock, typically dark in color. It forms when gas-rich lava is ejected from a volcano and cools rapidly, trapping the gas bubbles. While it's a volcanic rock, it's not specifically formed from the accumulation of volcanic ash.

*   **Option 4, Volcanic rock:** While tuff *is* a type of volcanic rock, this option is too broad. "Volcanic rock" is a general term that encompasses many different types of rocks formed from volcanic activity, including lava flows (basalt, rhyolite), pyroclastic rocks (tuff, volcanic breccia), and intrusive rocks that cooled near the surface. Tuff is a *specific* type of volcanic rock formed from ash accumulation, making Option 3 the more precise and therefore correct answer.