Around 1 billion years ago, what major continental-scale features were present?

• A. Supercontinents and Snowball Earth
• B. A single global ocean with no continents
• C. No atmosphere
• D. Abundant life with no oxygen

Answer: (A)

Around 1 billion years ago the big picture of Earth’s surface was dominated by a single or largely connected landmass—the supercontinent Rodinia. This arrangement is supported by clues in rocks that line up when continents are reassembled, similar fossil communities on now-distant shores, and magnetic data that point to a consolidated landmass rather than a scattered patchwork of continents.

The presence of a supercontinent at this time is the defining continental-scale feature. While later in the Proterozoic there were global ice-cover events often called Snowball Earth, those occur after this interval; the key takeaway for around 1 Ga is the existence of a major terrestrial mass rather than a completely ocean-covered world.