The winter crossing

An original fiction passage set in the nineteenth century.

The ice looked solid from the bank. In the middle of the river it became a cloudy window, showing the dark movement beneath. George kept his eyes on the opposite shore. His sister followed, carrying their bundle against her chest. Each step produced a small, sharp sound. Neither mentioned it. The far bank seemed to retreat whenever they looked up.

Then the surface sighed. George stopped so abruptly that his sister touched his back. A thin line appeared beside his boot and ran towards the reeds. He told her to move slowly towards the fallen branch near the bank. This time they watched the ice rather than the destination. When they reached the branch, he helped her over it and waited until both feet were on the earth before releasing her hand.

Analyse how the writer uses language and structure to show how the river threatens the travellers. Support your answer with references to the passage.