Kusawake district is located on the rolling hills extending over between Biei and Furano. You can observe the inside of the hills, since roads around Kusawake district were built by scraping the hills there.

You will find sparkling particles in looking at inside of the hills attentively. The particles are quartz. Including much quartz is a characteristic of Tokachi Pyroclastic Flow Deposit.

Tokachi Pyroclastic Flow was formed by eruptions of a volcano located at the centre of Hokkaido from 1.25 to 1.46 million years ago. The volcano used to exist on the northeast side of the Mt.Tokachidake. Pyroclastic flow is composed of volcanic ash, rock fragments, and volcanic gas. It flows along the ground away from the volcano at high speed, and high temperature. Gray cloud creeps onward along the earth unlike mudflow, and debris flow.