A layer of rock in a riverbank near Ichihara has given its name to a slice of Earth's history. In 2020, the international body that decides such things named a geological age the Chibanian, after a cliff on the Yōrō river where the last reversal of the Earth's magnetic field is recorded with unusual clarity. The site is small and muddy, reached by a short path, but standing in front of it is a strange experience, a few hundred thousand years of time in a single bank of clay.
Ichihara itself is a big city stretching from the industrial shoreline of Tokyo Bay, lined with refineries and petrochemical plants, deep into the rural hills of central Chiba. The inland part is a world away from the coast: rolling hills, rice terraces, forests and small villages. The Kominato Railway, a charming local line with old diesel trains, winds through the valleys and is especially beautiful during the cherry and rapeseed blossom season.
For riders, the inland roads are the highlight. The Yōrō valley, further south, is famous for its gorges, waterfalls and autumn colours, and the roads that wind through it are narrow, twisting and fun. The hills of the Bōsō peninsula are low, but they have plenty of curves and little traffic outside weekends. Surfaces are generally good, but watch for gravel and leaves on the corners.
Ichihara has fuel, konbini-style convenience stores and plenty of places to eat. The roadside stations in the hills offer local produce and snacks, and the onsen of the Yōrō valley are a good place to relax after a day of riding. The view across the hills, with layers of ridges fading into the distance, makes the climb worthwhile.