The Kitakami Mountains
The Kitakami mountain range is the oldest geological feature in Japan. The fossils found here show that this landmass moved up from a long way south of its present position.
In the Paleozoic era sediment that was underwater gradually rose up during a period between 250 and 400 million years ago to form this landmass, which became a peneplain after centuries of erosion and then rose up again to form a plateau-like mountain range featuring gently sloping mountains, of which Taneyamagahara is representative, and little valleys.

Taneyamagahara, one of the places Kenji was particularly fond of and where he often went walking, also holds an important position in his literary work. From here, Kenji would look out over the gentle rolling slopes of the Kitakami mountains and think what a refreshing spot it was. Mt. Monomi is 871 meters and affords a marvelous panoramic view---Mt. Iwate and Mt. Hayachine can both be seen from here.

Serpentine can be found at the top of Tane Mountain
"Tateyama and Tateyamagahara" (early version A of Tateyamagahara)
The monadnock in this highland
This is the peak of Tane Mountain
Melted by carbonic acid, rain, and every kind of reagent, it still stands
Dressed in moss and white
The rock, exposed, at the far edge
Of a summer's Alpine farm meadow . . .

Today, under the clean-swept sky
I stand on a large rock protuberance
The black mist has sunk down into the gentle peneplain and eroded valley
As far as the pale blue of that grim dead volcano to the north
The waves of land touch the sky
I look out over Ihatov prefecture
And see Ubaishi pasture just now
Born from the blue-green shadows of clouds
Look, hundreds of brown and white
Horses are gathered, moving
Swaying, shimmering in the haze . . .
The Complete Works of Miyazawa Kenji Vol.1, Chikuma Bunko

In the story Taneyamagahara Kenji describes the frequent and sudden climatic changes that occur on the mountain.

This was where the winds and moisture that came from the sea to the east and from the west always ran into each other, so it was a place where clouds, rain, lightening, or mist were always just about to happen.

Kenji was very sensitive to changes in the clouds, light, and the wind, so this was an important place for him.

@ "The cow's getting away. The cow's getting away. Hey, brother. Look, the cow's getting away."
The cow ran and ran, parting the tall grass as it went. Tatsuji, totally absorbed in the chase, went on running after it------
Tatsuji lay on his back, looking up at the sky. The sky flashed a pure white, spun round and round, and the light gray clouds nearby raced farther and farther away, all the while sending out thunderous sounds.------
The sky grew dark and heavy and all around him it began to grow dim. A cold wind moved over the grass, and fragments of clouds and mist passed steadily in front of his eyes.
"Tanayamagahara" fromThe Complete Works of Miyazawa Kenji Vol.5, Chikuma Bunko

The Four Seasons in Ihatov Natural Features in Ihatov