A new study shows that some komatiites — cooled lava that flowed on Earth as long as 2.5 billion years ago — may be much younger and hotter than geologists previously thought.

The discovery: Geologists recently found evidence of 89 million-year-old komatiites in Costa Rica. "These are very, very young," said Esteban Gazel, author of the study, told Popular Science. "In geologic terms, 89 million years ago is like it happened a second ago."

Why it's so startling: Most komatiites originated during the Archean age, between 4 billion and 2.5 billion years ago, when Earth's interior was so hot that some lava flows were white instead of red. Since then, Earth's mantle has cooled by about 500 degrees Fahrenheit, but the discovery of these newer komatiites suggest deeper areas of the planet have maintained the hot temperatures of the Archean period.

Why it matters: "What is really fascinating about this study is that we show that the planet is still capable of producing lavas as hot as during the Archean time period," Gazel said in a statement. "Based on our results... we think that mantle plumes are 'tapping' a deep, hot region of the mantle that hasn't cooled very much since the Archean. We think that this region is probably being sustained by heat from the crystallizing core of the planet."

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