he burst clear just short of a towering white mountain-face , stark against the open blue , and temeraire roared as he came : a hammer-blow against the solid-packed ice and snow ; laurence clung to the harness , shivering involuntarily , as temeraire pulled up nearly vertical , climbing along the face of the mountain , and the pursuit came chasing out of the clouds only to recoil from the thundering , rolling , steady roar of avalanche , coming down upon them like a week 's snowstorm compressed into a heartbeat : the winchesters all squalling alarmed , and scattering away from it like a flock of sparrows .