In the environs of the south-western Shimofurano, the western end of the Yubari mountains in the Kamuikotan tectonic zone, a small area of hornfels has recently been found, though it has been considered as the characteristic area of the low grade metamorphosed schist.
Around the said area, the pre-Cretaceous and overlying lower or middle Cretaceous formations are disposed with N-S trend. Cutting these Cretaceous shales, many trondhjemite dikes are found with the prominent feature in this zone. It is conclude that the hornfels is closely related to the intrusion of the trondhjemite dikes.