312 OUR NATIONAL PARKS 



taneously, and with awful roaring and throbbing 

 a round, tapering flame shoots up two or three 

 hundred feet, and in a second or two is quenched, 

 leaving the green spire a black, dead mast, bris- 

 tled and roughened with down-curling boughs. 

 Nearly all the trees that have been burned 

 down are lying with their heads uphill, because 

 they are burned far more deeply on the upper 

 side, on account of broken limbs rolling down 

 against them to make hot fires, while only leaves 

 and twigs accumulate on the lower side and 

 are quickly consumed without injury to the tree. 

 But green, resinless Sequoia wood burns very 

 slowly, and many successive fires are required to 

 burn down a large tree. Fires can run only at 

 intervals of several years, and when the ordinary 

 amount of firewood that has rolled against the 

 gigantic trunk is consumed, only a shallow scar 

 is made, which is slowly deepened by recurring 

 fires until far beyond the centre of gravity, and 

 when at last the tree falls, it of course falls uphill. 

 The healing folds of wood layers on some of the 

 deeply burned trees show that centuries have 

 elapsed since the last wounds were made. 



When a great Sequoia falls, its head is smashed 

 into fragments about as small as those made by 

 lightning, which are mostly devoured by the first 

 running, hunting fire that finds them, while the 

 trunk is slowly wasted away by centuries of fire 

 and weather. One of the most interesting fire 



