shin up the face

角田光代の "The Eighth Day" (原題　八日目の蝉)を読み始めました。　10年程前にテレビ化された八日目の蝉を観た覚えがありますが、 "The Eighth Day" を三分の一程まで読んでも内容を思い出せません。でも日本が舞台の小説は英語でも分かり易いですね。
After praying at Ryukoji Temple, we started up a long stone stairway lined with stone lanterns on both sides. We climbed the steps, following the signs, until we found ourselves looking up a stretch of bare rock. Metal poles had been pounded into the rock, connected by chains. These were to grab hold of as you pulled yourself up the steep trail.
"Kaoru, do you mind waiting for me here?"
"Sure, I'll wait," she said, squatting down where she was. I grasped the chain and started up. I'd climb a little way and then, to make sure she was still there, shout her name, "Kaoru!" Each time she yelled back, "Mama!"
As I shinned up the face, I thought how peculiar I must look to an observer, hanging on to these rusty links of chain as I called out my daughter's name.

"shinned up the face" の "shin" も "face" も体の一部なので何かと思いましたが、文脈からして "shinned up" は横に支えとなるチェインがある急坂を登っているに違いありません。辞書を見ます。
・Oxford English Dictionary: shin up/down Climb quickly up or down by gripping with one's arms and legs.: he shinned up a tree

・Wiktionary: o climb a mast, tree, rope, or the like, by embracing it alternately with the arms and legs, without help of steps, spurs, or the like.: to shin up a mast

・Cambridge English Dictionary: to climb something such as a tree, using your hands and legs to move along quickly: Several of us shinned up lampposts so that we could see over the crowd.
"shinned up" が登る意味なのでこの個所の "face" は顔ではなく急な斜面を意味しているはずです。
・Oxford English Dictionary: A vertical or sloping side of a mountain or cliff.: the south face of Broad Peak

・Collins Dictionary: The face of a cliff, mountain, or building is a vertical surface or side of it.
...the north face of the Eiger.: He scrambled 200 feet up the cliff face.