The Precambrian era envelopes the major bulk of the history of the Earth, beginning from the creation of the planet approx 4.5 billion years ago and terminating with the origination of composite, multicelled forms of life approximately 4 billion years after.
The Precambrian refers to the earliest of the geologic ages that are signified by the distinct layers of sedimentary rock. The Earth was about more than six hundred million years old when life started. The planet had cooled down from its native molten state, creating a solid crust and oceans formed by water vapor in the atmosphere.
At about three billion years ago, the atmosphere of the Earth was virtually devoid of oxygen. At approximately 2.4 billion years ago, oxygen was discharged from the seas as a waste product of photosynthesis by cyanobacteria. The levels of the gas slowly raised, attaining about 1 percent around two billion years ago.
Approximately 800 million years ago, the levels of oxygen attained about 21 percent and started to breathe life into more composite species. The oxygen-rich ozone layer was also created, protecting the surface of the Earth from the harmful solar radiation.
Answer:
The Rf values indicate how soluble the particular pigment is in the solvent by how high the pigment moves on the paper.
Explanation:
The Rf values indicate how soluble the particular pigment is in the solvent by how high the pigment moves on the paper. Small Rf values tend to indicate larger, less soluble pigments while the highly soluble pigments have an Rf value near to one.
C. Shield Volcano.. think of Hawaiian volcanoes,they are basaltic eruptions, very effusive and unexplosive and are characterised by slow lava movement and very little tephra from the eruption. The basalt erupted is very hard, dense rock and so can be built up easily.
Answer:
Adirondacks "Missing Time" Formation
