Geologists have long marveled at the slow, earth-shaking dance performed by those colossal blocks of land known as continents. Over the course of hundreds of millions of years, the seven continents commonly known today have shifted and buckled, occupying various positions overlaying the earth’s molten interior—like shuffling dominoes on a table. Researchers may now have discovered evidence for what could be nothing short of the world’s eighth continent: Zealandia, situated under the islands of New Zealand. Their findings were published in a study supporting the claim. Its authors gathered crystal samples, from two distinct geologic provinces, containing low amounts of an oxygen isotope called O-18—indicating that Zealandia has a continental core of rock (called a craton), a foundation common to all the other continents, dating from the Rodinian age. The fact that the Proterozoic supercontinent of Rodinia existed some 0.9–1.1 billion years ago—when all or most of the continents composed one larger one—lends …