Final answer:
Muir's "Calypso Borealis" exhibits a tone of awe and adventure, as well as challenge and endurance, created through his vivid descriptions of nature’s beauty juxtaposed with the hardships of exploration.
Step-by-step explanation:
Tone in a piece of writing is created by the choice of words and the imagery used to convey the author's feelings and attitudes toward the subject matter. In Muir's "Calypso Borealis", the tone can be described as one of awe and adventure, blended with a touch of hardship. The author describes his immersion in nature with phrases such as "botanising in glorious freedom" and "rejoicing in their bound wealth and strength and beauty", which create a sense of wonder and deep appreciation for the environment. Contrastingly, he also recounts the difficulties of his journey, referring to fording streams and wading through swamps, which injects a tone of challenge and endurance. These elements together build a rich and multifaceted tone that conveys both the beauty and the struggles inherent in his explorations.