Answer:
the atmosphere
Explanation:
When studying ice cores, we can sometimes encounter gases in them. These gases are often trapped in pockets of ice crystals.
Glaciers which are the origin of ice cores forms like sedimentary rocks. They undergo a lot of compression and compaction under their own weight. This leads to decrease in porosity and permeability between ice flakes. The prevalent atmosphere during their time of formation contributes gases that finds their way into pore spaces. These gases can collect into small pocket and survive the glaciation process.
These gases tells us about the atmospheric condition in the area the core was obtained.
