The 'horn' in hornfels is German for horn, referring to the rock's extreme hardness.
The stratification is the result of magma from a volcanic eruption 14 million years ago baking the surrounding sedimentary rock.
The formation is widely considered one of the finest examples of hornfels in Japan.
The rock layers are often compared to the pages of a book due to their distinct, rhythmic, and parallel coloration.
The Susa Hornfels is a massive geological formation located on the northern coast of Hagi, Yamaguchi Prefecture. It consists of alternating black and white layers of sedimentary rock that were transformed by contact metamorphism when magma intruded into the shale 14 million years ago. These distinctive, sharp-edged strata extend into the Sea of Japan, creating a rugged, wave-battered shoreline. The site is part of the San'in Kaigan Geopark area, highlighting the region's volcanic history. Visitors can walk along the coastal cliffs to observe the geometric patterns of the metamorphosed rock. The site is a designated natural monument of Yamaguchi Prefecture. The name 'hornfels' refers to the rock's hard, splintery texture resulting from high-heat exposure.
From the lower observation platform looking back at the stratified cliff face against the sea.
Wear sturdy, non-slip footwear as the rock surfaces can be uneven and slippery near the water.
Stay on designated paths, as the cliffs are steep and unsecured.
Check the local tide schedule before visiting, as high tide can limit access to the lower rock shelves.
Do not attempt to walk on the rock edges during high winds or heavy surf, as the waves can reach the lower levels.
Practice 'leave no trace' principles; do not remove or chip away any rock fragments from the formation.
