“I wasn’t that brave. In fact I was having enough difficulty staving off the dread which through me as I descended”
This talks about how his emotions are just as much of a burden as his physical condition. He states he has too much difficulty preventing his anxious feelings. The dread term is used as almost like a person. Like a person that Joe is trying to hold back with a massive effort that is slowly besting him in his fight. When he says the dread swamped through him it is powerful. You ascociate swamps as dark thick sludgy liquids with scary unknown inhabitants dwelling in the murky bottom. You can relate the dread as a ferocious beast, a predator which flows through the swamp. But this is a disguised swamp. You can relate the mountain to a swamp without relating it to this quote. It’s unknown, has a sense of mystery. You wouldn’t be surprised if you died inside or on it. And many people have made up ‘mystery’ creatures such as big foot/yeti and the Loch Ness monster. when traveling through the ice of the glaciers it feels like a swamp as your mobility is limited.