The age of thethe theory of incorporates the ideas of both seafloor spreading and continental drift into a unified model. sea floor away from the ocean spreading centers.

Given question is in incorrect format as it is a mixture of two questions. The two questions are as follows :

(1) The theory of incorporates the ideas of both seafloor spreading and continental drift into a unified model.

(2) The age of the sea floor away from the ocean spreading centers.

1- Plate tectonic

2- Increases

Explanation:

The plate tectonic theory describes the movement of the tectonic plates from one place to another due to the generation of convection current in the mantle. It is possible due to the heat supplied from the interior of the earth. It is the key to the understanding of both the seafloor spreading and the continental drift.

The seafloor spreading takes place in a divergent plate boundary, forming a mid-oceanic ridge, through which the magma from the interior of the earth comes out at the seafloor. The rocks that are deposited and formed in and around this ridge are the geologically youngest rocks. And as one travels away from the mid-oceanic ridge, the age of the seafloor increases.

the density would be a smaller number.