Glaciologists, geochemists, and climatologists study ice layers to learn about past climates. Distinct ice layers are caused by . When studying ice layers, scientists use to measure isotopes of certain gases. These gases reveal the at the time when the ice layers were formed.

1. Seasonal changes

2. Spectrometers

3. Temperature

Explanation:

the conditions that made the byzantine empire vulnerable to attacks by the muslin turks were the sack of constantinople by western crusaders, the conquests of the sultanate of rum, presence of rival kingdoms and finally the set up of fiefdoms at the empire which were owned by the ghazis (turkish warriors).

increase in population