310 GEOLOGY OF THE BLACK HILLS. 



Severe thunder-storms prevail in the Black Hills during the summer 

 months. The clouds, instead of floating high in the air, sweep low over 

 the elevated ridges, and the lightning is consequently peculiarly liable to 

 strike the ground rather than to pass from one portion of the cloud to 

 another and harmlessly expend its force. This causes some damage to the 

 timber of the region. Often, in riding through the Hills, trees showing 

 unmistakable marks of lightning would be seen, generally with the top 

 shattered and a strip of bark about an inch wide torn out in a straight or 

 spiral line from the top of the tree to the ground. Sometimes, however, 

 only the splintered stump of what had once been a large tree remained, 

 while the ground all around was strewed with fragments of the trunk, 

 branches, and limbs. 



It would seem that the pines growing in certain portions of the Hills 

 were peculiarly liable, for some unknown reason, to be struck by lightning. 

 On a hill near the headwaters of Spring Creek I counted twelve trees, 

 growing on about two acres of ground, that were marked by lightning, and 

 in a small park near by, among about one hundred trees, fourteen had been 

 struck in previous years; some of them more than once. The most severe 

 thunder-storms came from the west and traveled in an easterly or south- 

 easterly course, the storm commencing with gusts of wind from the west, 

 shifting to the north and northeast in the height of the tempest, and finally, 

 as the storm passed by, blowing from the east or southeast. 



A most terrific thunder-storm was encountered by myself and a small 

 party of miners while camped on Box Elder Creek, August 7. The day had 

 been pleasant but somewhat warmer than usual. About 3 o'clock in the 

 afternoon a dense black cloud, extending like a wall across the valley, and 

 rapidly advancing from the west, warned us of the approaching storm. 

 Hardly had we completed our preparations to protect ourselves and provis- 

 ions from the rain, when, preceded by violent gusts of wind that nearly 

 prostrated every tent, the storm burst upon us. The rain, impelled by the 

 violence of the wind, descended almost horizontally, and beat in torrents 

 against the sides of the tents for about five minutes. Then, suddenly the 

 wind shifted to the north, and came in sudden squalls of cold, piercing 

 wind, chilling us through in a moment, and changing the rain instantly to 



