bisect it

[unpakwon]

Could anyone help me with the following in bold? They are climbing Mount Rainier.

Once past the Cowlitz Glacier, we made it to Cathedral Rocks, which is a huge rock formation that runs vertically up the mountain. We had to bisect it at a place called Cathedral Gap, which required us to go up and over the rocks. It was steep and a hassle to climb in crampons.

In the above, I'm confused about the meaning of "bisect," although I know its literal meaning. Is it saying "we had to intersect or cross the middle part of Cathedral Rocks?"

Thank you.

[Mister Micawber]

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I think, just climb over it (intersect/cross)-- not necessarily in the middle, but they couldn't go around it.
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