Logan is a name with Irish origins. The meaning of the name Logan is from the hollow. Common nicknames for Logan include Loag and Lo. Famous Loganâs include athletes Logan Bailly, Logan Coutre, Logan Kensing, and Logan Mankins.
During the Cambrian explosion, the atmospheric oxygen levels increased by up to 10 percent, and prior to that time the living creatures roaming the Earth were typically small, simple and often single-celled.
Life itself, in other words, turned earthâs vacuum back up again. By 2 billion years ago, oxygen levels were down to about 0.01 percent of current levels. Life and earth have continued to twiddle the oxygen knob over the past two billion years. When plants evolved, for example, they began storing huge amounts of carbon in wood and other tough tissues, leaving less to react with oxygen and pull it out of the atmosphere. By 300 million years ago, oxygen had risen to levels as high as 50 percent higher than today. But as continents moved across the globe, the planetâs geography came to favor deserts. Forests shrank, bringing down the oxygen levels.