Final answer:
The shift to the present tense when Walton is writing creates immediacy and makes the events of the story feel more vivid and immediate to the reader.
Step-by-step explanation:
When Walton is writing, the text shifts to the present tense. This shift to the present tense has the effect of creating immediacy and making the events of the story feel more vivid and immediate to the reader. It helps to engage the reader and bring them into the story as if it is happening in real time.