From 9,000 ft (2,700 m) to 11,000 ft (3,400 m),[72] the montane forests give way to subalpine forests.[69] Forests of fir and Engelmann spruce cover the mountainsides in subalpine areas. Trees grow straight and tall in the lower subalpine forests, but become shorter and more deformed the nearer they are to the tree line.[72] At the tree line, seedlings may germinate on the lee side of rocks and grow only as high as the rock provides wind protection, with any further growth being more horizontal than vertical. The low growth of dense trees is called krummholz, which may become well-established and live for several hundred to a thousand years old.[72]
The sun made us lazy, and after following Brian as he made his way upstream I found a wider expanse of sand and gravel, promptly plopping down on a pair of flip flops I had brought in my backpack as a make-shift seat. After identifying the northern harrier hawk over my head, and the savannas sparrows and red-winged blackbirds perched precariously on reeds across the water, I took out my knitting project. I didn’t have to worry about losing Brian; in the valley I could see for miles in both directions. 
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