The inner part of the Earth, consisting of the core, is more dense than the outer layers due to several factors. The Earth's core is made up of a solid inner core and a liquid outer core, both of which contribute to its higher density.

1. Pressure: The immense pressure at the Earth's core compresses the materials, causing them to become denser. As you move towards the center of the Earth, the pressure increases, compacting the materials and increasing their density.

2. Composition: The core is composed primarily of iron and nickel, which are dense materials. The high concentration of these heavy elements contributes to the overall density of the core.

3. Temperature: The core of the Earth is extremely hot, reaching temperatures of about 5,000 degrees Celsius. This high temperature causes the materials to expand and become less dense, but the immense pressure at the core counteracts this effect, resulting in a net increase in density.

4. Gravitational Compression: Over the Earth's history, gravitational forces have acted to compress the materials in the core, further increasing their density.

These factors combine to make the core of the Earth significantly denser than the outer layers. The density gradient from the core to the surface is one of the key factors that contribute to the Earth's gravitational pull and its overall structure as a planet.