There's a bit of a misunderstanding in the question. The mantle is a layer beneath the Earth's crust. It's not a part of the crust.

Here's a breakdown of Earth's layers:

1. Crust: The outermost layer, thin and rocky, with two types:

* Continental crust: Forms the continents, thicker and less dense.

* Oceanic crust: Forms the ocean floor, thinner and denser.

2. Mantle: The thickest layer, mostly solid rock but with a semi-molten layer called the asthenosphere.

3. Outer Core: Liquid iron and nickel.

4. Inner Core: Solid iron and nickel.

So, there is no "lower part of the mantle in the crust". The mantle lies beneath the crust.

Let me know if you have any other questions about Earth's structure!