Answer:
between 20,000 and 25,000
All rock on the ocean floor is less than 180 million years old because <span>reverse polarity removed older rock strips magnetized in a different direction. Also,</span> the oldest parts reach the continental crust and then the ocean floor sinks beneath the continental crust, into the mantle.
<em>Answer: From 1990 to 2019, the total warming effect from greenhouse gases added by humans to the Earth's atmosphere increased by 45 percent. The warming effect associated with carbon dioxide alone increased by 36 percent.</em>
