Heyy can you help will mark brainlist 1) What was the Earth's first atmosphere like?
Predominantly hydrogen and helium, much like Jupiter and Saturn
Mostly nitrogen, carbon dioxide, water vapor
Mostly nitrogen and about 15% oxygen
Methane, hydrogen and ammonia

2) What do climatologist study about fossil seashells in rock sediments to learn about climate?
the ratio of magnesium to calcium in the shells
the chemical traces of alkenones
the strontium content
the shapes of the shells

Our atmosphere is very different from that of planets such as Venus and Mars. ... oxygen, with traces of other things like water and carbon dioxide. ... Jupiter and Saturn are dominated by hydrogen and helium, The thick ... Like most planets Earth's earliest atmosphere was dominated by hydrogen and helium

Explanation: Sediments and rocks record changes in atmospheric composition from ... Earth's original atmosphere was rich in methane, ammonia, water vapour, and the ... atmosphere was largely made up of nitrogen and carbon dioxide gases. ... and in the oceans, much of the carbon dioxide was replaced with oxygen.

CO2 and other gases trap heat and keep the surface warm enough for life to thrive. ... Each of the planets has a different atmosphere, although there are clear similarities between the ... The Earth's atmosphere primarily composed of nitrogen and oxygen. Hope this helps you