86 ice Caves. 



Macrochaeta of legs wholly Macrochaeta of legs largely 



yellow. black. 



Eyes in death deep green. Eyes in death dark brown, 



with a purplish tinge. 



Length, excluding the pro- Length, excluding the pro- 



boscis, 22 mm. boscis, 27 mm. 



Expanse, 40 mm. Expanse, 46 mm. 



D. W. Coquillett. 



ICE CA VES. 



(Written for the Oregon Naturalist.) 



Caverns in recent lava flows are often observed by travelers. 

 In the neighborhood of Mt. Adams, in Washington, there are 

 some singular caves in basalt which were lately described to the 

 writer by a friend who has visited them and who offers the fol- 

 lowing explanation pi their formation. One of these possessed 

 the unusual features of a fine supply of the purest ice, hanging in 

 great pillars from the roof of the cave, and swelling out in great 

 masses from the sides. These caves are quite numerous in the 

 region drained by the upper waters of the White Salmon river. 

 Years ago sufficient ice was obtained from one of these to supply 

 the city of Portland, Oregon, the ice being packed on mules to 

 the Columbia river, and thence by steamer. 



A curious fact was observed, that the ice was formed in the 

 spring and not in the winter season. These caverns are long pas- 

 sages through which lava once flowed in diminished volume after 

 an eruption. In some of these passages the opening through 

 which the lava entered the chamber would become choked up, 

 or the flow otherwise interrupted or diverted into another chan- 

 nel, and the liquid portion remaining would then flow out, leav- 

 ing an empty chamber. Some of these passages extended from 

 the crater above to the plains below, and such are the ice caves 

 according to the following evidence 



First, the unquestionably volcanic character of the cave ex- 

 amined, with its ropy masses of hardened lava, all trailing in the 

 direction of the lava flow. 



Second, a cold, freezing wind escaping from the mouth of the 

 cave, cold enough at night in August to freeze. 



Third, the observed fact that the ice cut away was replaced in 

 spring and early summer, through April, May and June 



The lower opening being in a warmer atmosphere than the up- 

 per opening, causes a downward draft through the passage of cold 

 air, which, it is obvious, freezes the water trickling from the sides 

 and roof of the passage as it passes. 



