in Thoreau’s Journal:

At 9 A M up river to fair Haven Pond. This is our month of the crusted snow. Was this the Indians? I get over the half buried fences at a stride—and the drifts slope up to the tops of the walls on each side. The crust is melted on the S slopes and lets me in—or where the sun has been reflected (yesterday) from a woodside—& rotted it, but the least inclination to the north is evidence of a hard surface—  On the meadows and in level open fields away from the reflection of pines & oak leaves it will generally bear.