Geology

A well-known natural sea arch along Hawaii’s coastline collapsed into the Pacific Ocean this week without warning, ending a roughly 550-year run as both a geological landmark and a tourist draw. The arch had been carved from volcanic rock by centuries of wave and salt weathering, and its loss has renewed discussion among researchers and the public about how fast coastal landforms evolve, whether sea-level rise is accelerating erosion, and how complete the human record of such long geological processes can ever be.

A new analysis combining data from NASA’s MESSENGER mission and the European BepiColombo probe shows Mercury is shrinking far faster than scientists had previously believed, with global contraction leaving visible fault scarps across the planet’s surface. Researchers say the rate of cooling and contraction carries major implications for understanding the thermal evolution of small rocky planets, the durability of their magnetic fields, and the broader geological history of the inner solar system. The findings also raise fresh questions about how Mercury has retained a magnetic field despite being a small planet with a slowly solidifying inner core, a long-standing puzzle in comparative planetology.

Scientists found the crust beneath East Africa’s Turkana Rift is thinning to a critical point, suggesting the continent’s breakup is at a more advanced stage than previously thought.