HAWAII, November 14, 2026 — A formation resembling a yellow brick road was filmed on the Pacific seafloor at 1,029 metres depth during a 2022 E/V Nautilus expedition near Nootka Seamount. Scientists identified the feature as fractured hyaloclastite, a volcanic rock whose right‑angled grids record the thermal shock and cooling cycles of Pacific‑plate hotspot eruptions.
The Discovery on Liliʻuokalani Ridge
The Ocean Exploration Trust’s research vessel E/V Nautilus was surveying the Liliʻuokalani Ridge north of the Hawaiian archipelago from April 7 to May 1, 2022. No previous expedition had mapped this stretch of seamounts. During a live‑broadcast dive at the summit of Nootka Seamount, 3,375 feet (1,029 metres) below the surface within the Papahānaumokuākea Marine National Monument, the remotely operated vehicle’s lights revealed a regular, brick‑like pattern of right‑angled cracks on the seafloor. The crew nicknamed it the “yellow brick road.” The monument covers roughly 582,000 square miles, yet only about three percent of its seafloor has been mapped.
What Hyaloclastite Is and How It Forms
Hyaloclastite is a volcanic rock created when hot magma meets near‑freezing seawater. The extreme temperature difference shatters the lava into glassy fragments almost instantly. At depths exceeding 3,000 feet, immense water pressure compresses the cooling rock while cold currents accelerate structural cracking. This rapid quenching and continuous hydraulic pressure give deep‑water hyaloclastite textures distinct from similar fracture patterns seen in land‑based basalt formations such as the Giant’s Causeway in Northern Ireland.
Thermal‑Shock Fracturing Creates the Grid
The clean 90‑degree grids on Liliʻuokalani Ridge result from repeated eruptions and cooling cycles. Each pulse of lava forms a crust that fractures under the stress of intense heating followed by rapid cooling. The uniform stress distribution in the cooling lava sheets naturally yields perpendicular jointing. Low‑temperature hydrothermal alteration of the volcanic glass later deposited iron oxyhydroxide in the cracks, giving the surface its distinctive yellow colour and highlighting the rectangular borders.
What the Formation Tells Us About Pacific Hotspot Volcanism
The fractured hyaloclastite provides a visual baseline for studying underwater thermal stress and the eruptive history of the Pacific plate. Scientists log physical specimens to establish accurate timelines for hotspot activity across the Pacific Basin. The expedition recovered 178 biological and geological samples that are being used to refine those timelines. Mapping isolated seamount structures like Nootka also helps oceanographers evaluate slope stability and regional acoustic properties.
Implications for Seafloor Mapping and Future Research
The discovery demonstrated a new model for deep‑sea research. The live‑broadcast telepresence approach allowed geologists thousands of miles away to collaborate with the shipboard navigation team and analyze the formation in real time. The Ocean Exploration Trust relies on these high‑definition feeds to catalog remote seamounts. With 97 percent of the Papahānaumokuākea seafloor still unmapped, such expeditions remain crucial for understanding Pacific‑plate volcanic history.
Sources
- A âyellow brick roadâ was discovered 1,029 metres beneath the Pacific Ocean; scientists explain how volcanic rock and iron-rich deposits created the striking formation
- Hawaii
- A deep-sea camera north of Hawaii found what looked like a yellow brick road on the seafloor. The crew's first guess was "the road to Atlantis" – Futura-Sciences
Photo: Artists Eyes / Unsplash (Unsplash License)
