The lingering warmth of the dissipating light still clung to Ayu's eyelashes, and the ashes of the unmailed letters hung in circles before her eyes. They weren't regular concentric circles, but more like tree rings washed by water, each ring bearing natural unevenness—the outermost layer of ash particles was sparse, trembling slightly in the wind, and upon closer inspection, one could discern fine lines, much like the sedimentary rock profile on the western shore of Qinghai Lake, where translucent shell fragments were embedded in layers of sandy rock, fingerprints left by the rise and fall of the lake over millions of years.

"Don't move." Zhong Hua's fingertips hovered two centimeters in front of the gray ring, the warmth of his fingertips causing the nearest few grains of ash to tremble slightly. He remembered that last year on the cliff edge on the west bank of Qinghai Lake, the guide had used a geological hammer to break open a piece of sedimentary rock, and the layered structure inside was surprisingly consistent with the gray ring at this moment. "Each layer of rock texture corresponds to a rise and fall of the lake level, just like the diary of the earth."

Following his fingertip, Ayu noticed that the second layer of the gray ring was significantly denser, with fine white marks embedded among the gray particles, like scratches from a sharp weapon. These were glacial striations from the cirque in Yubeng Village, the same kind they had seen on the rocks below the Sacred Waterfall last year—glaciers carrying rocks rolled over the mountain, carving grooves of varying depths into the hard granite, the deepest of which could fit an entire palm. Now, those white marks meandered within the gray ring, perfectly matching the direction of the glacier's flow in her memory, as if an invisible force had imprinted the texture of the snow-capped mountain into the ashes after burning.

“The core is glowing,” Ayu’s voice trembled. The ash at the very center of the gray ring didn’t disperse; instead, it solidified into a translucent sphere, filled with honeycomb-like pores, the walls of which gleamed with a metallic sheen. That was the vesicular structure of the volcanic rock of Weizhou Island. They had seen the crater hollowed out by the waves at Crocodile Mountain Scenic Area last year; the black basalt was covered with such pores, nests left behind by gases escaping as the magma cooled. At this moment, these pores were slowly opening and closing in the core of the gray ring, like some kind of breathing. With each contraction, extremely fine dust particles of light overflowed from the pores and fell onto the outer gray ring.

Zhong Hua suddenly remembered the geological compass in his backpack. As he frantically unzipped it, Ayu had already counted the number of ash rings—exactly seven layers. The compass needle spun wildly in front of the ash rings, finally stopping at a 33-degree angle, exactly the same as the magnetic declination they had measured at the Weizhou Island volcano. "Look at the thickness," he said, aligning the compass markings with the cross-section of the ash rings. Ayu then noticed a subtle difference in the thickness of each ring of ash: the outermost layer was the thinnest, about the thickness of two sheets of paper stacked together, while it thickened towards the center, reaching the width of a little fingernail by the third layer.

“1999.” Zhong Hua’s fingertip landed on the outermost gray circle, which suddenly turned a very pale yellow, like the yellow stains on the edge of an old postcard. He remembered that postcard that had been poured out of the old mailbox; the postmark “1999.07.16” was long since blurred, but the moment his fingertip touched it, it was clearly reflected on the surface of the gray ring. Ayu’s breath hitched. In 1999, she had just started elementary school, and her mother was still embroidering that unfinished peony painting in the attic, the silk threads gleaming in the sunlight with the same warm yellow as the gray ash now.

Her fingertip moved in half a centimeter, and the gray ring turned a light blue. That was 1997, the year Zhong Hua was born. Tucked in his grandfather's logbook was a ship ticket from that year, the shape of the seawater stains along the edge of the ticket stub perfectly matching the arc of this gray ring. Ayu suddenly remembered a photo in Zhong Hua's family's old album: him as an infant, wrapped in a blue swaddle, with his grandfather's ship in the background, the wave patterns on the ship's hull perfectly matching the light blue ring.

“Further in…” Zhong Hua’s fingertip hovered over the third gray ring. That ring of ash was a deep bluish-gray, like a frozen lake. He pulled a small, sealed bag from his backpack, containing an ice core sample drilled last year at Namtso Lake—a translucent ice column containing tiny air bubbles, air from hundreds of years ago. Friends on the expedition team had said that this ice core recorded the sharp temperature drop during the Little Ice Age of the Ming and Qing dynasties, and carbon-14 dating showed it formed around 1600 years ago. At that moment, the core of the gray ring suddenly emitted a faint glow, projecting a string of numbers into the air, perfectly matching the dating values ​​on the ice core report.

Ayu's fingernails dug into her palm. In 1600, she had seen a related record on a mural in the Mogao Grottoes of Dunhuang. Next to the inscription of a donor on a certain Tang Dynasty mural, there was a later addition in cinnabar: "In a year of great famine, the river was frozen three feet thick." The strokes of the characters overlapped with the edge of the pores in the core of the gray ring, as if someone had used an invisible pen to carve the same mark on the rock layer of time.

A gust of wind blew in through the broken window of the waiting room, and the gray rings suddenly began to spin. At first, it was slow, like the swing of a pendulum, but gradually, the rotation speed increased, and the patterns between the gray grains began to blur, forming a band of light interwoven with blue, cyan, and yellow. Zhong Hua took out his phone and played an audio recording he had made last year at the Singing Sand Dunes—it was the sound of sandstorms passing through camel bells. The guide had said that the sand grains at the Singing Sand Dunes always fell downwards at a constant speed, 0.3 meters per second, a unique tempo of the desert. He turned up the volume on his phone, and the moment the sound of the sandstorm echoed in the empty waiting room, A Yu suddenly exclaimed, "Spinning speed!"

The angular velocity of the rotating gray ring was perfectly synchronized with the rhythm of the sand grains sliding down in the audio. She recalled a moonlit night last year at Mingsha Mountain, when they shone flashlights on the flowing sand dunes, and the arcs formed by the tumbling sand grains perfectly matched the band of light from the rotating gray ring. Even more astonishingly, the shadows cast on the ground by the airflow generated by the rotating gray ring were exactly the same as the contour lines of Mingsha Mountain, as if the entire desert had been compressed into this ring of suspended ash, recreating millions of years of wind and sand history before their eyes.

“Look at the core.” Zhong Hua’s voice trembled almost imperceptibly. As the rotation accelerated, the pores in the volcanic rock at the core of the gray ring began to glow, each pore emitting tiny spots of light. These spots connected to form lines, creating a microscopic structure of the Namtso ice core—the frozen air bubbles slowly expanding within the gray ring, like lungs breathing. Ayu suddenly remembered what the old herdsman had said by the shores of Namtso Lake: “The lake water remembers all the winds that have passed, and the ice core remembers all the snow that has fallen.”

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