As you travel from a spreading center towards a coastline what happens to the age of the rocks of the sea floor

- Age increases toward coastline and deposition also increase.

For two reasons:

1- The most significant reason is that continental crust is a primary source of sediment in the ocean. All sedimentary packages thin away from the continent toward the ocean ridges.

2- The oceanic crust is youngest at the oceanic ridges and so, therefore, have had less time for sediment (mostly pelagic "rain'' ) to accumulate on them.

- New crust is being created along the divergent plate boundaries and forcing the older crust towards the coastlines. The observation of the oldest crust is far from the boundary and the newest crust being right along it supports the idea that the plates are diverging.

Gas will most likely  fill the container