How do we know there was an ocean on the Earth 4.28 billion years ago?

What is the name for a substance formed in a chemical reaction

Which two factors contributed to creating a global culture? the creation of the united nations improvement in telecommunications health issues such as the ebola virus increased opportunities for global travel

Which set of characteristics best describes sedimentary rock? a) largest type of rock, made of organic matter, hardest type of rock b) often contains layers, forms near sources of water, contains fossils c) least abundant type of rock, made of other rocks, made mostly of minerals d) most abundant type in earth's crust, made of magma/lava, contains no fossils