CLIFF OF ALUM SLATE. 169 



ances promised a chance of landing. The water was bold to within 

 three or four boats'-length of the pebbly shore, but the men were 

 obliged to get into the water and carry the baggage to land, and 

 thence nearly a quarter of a mile to the foot of the mountain, be- 

 fore finding ground upon which to encamp. Several of them were 

 quite unwell from previous exposure, and all were jaded, stiif, and 



sore. 



^ The nearest water was two miles distant, and had to be carried 

 m India-rubber bags and kegs upon the shoulders. No breakfast 

 was to be had until near noon, and the remainder of the day was 

 devoted to rest and to drying our clothing and bedding. The sun 

 was bright for most of the day, but the wind was keen and cold. 

 ^ Ihe presence or absence of the sun in this climate has a marked 

 influence upon the temperature. The day may be oppressively 

 warm, but as soon as the sun disappears behind the western moun- 

 tarns, a fire is indispensable to comfort. The morning early may 

 be very cold, but soon after the appearance of the sun, cloth coats 

 become uncomfortable. Should the sun become overclouded for 

 any length of time, they are resumed. 



^ Segos are here very abundant, and of a large size, and are found 

 m every tuft of bunch-grass. In the vicinity, a clifi" was discovered 

 ot alum slate, nearly a mile in length, and about sixty feet in 

 height above the lake. It is traversed by several dikes of 

 trap, with cubical crystals of iron pyrites, and by one dike of 

 quartz rock. The slate contains numerous veins of very pure 

 fibrous alum. Between this cliff and Promontory Point there, 

 occur strata of mica slate, fine grindstone-grit, sandstone, and 

 albite. 



Friday, April 19.-Rain during the night. Morning wet, cold, 

 and raw Nevertheless, we started in the boat for a large island 

 west of Antelope Island, which the officers of the party had done 

 me the honour to call by my name. After erecting a station upon 

 Its northern point, it was my intention to proceed to Blach Rock 

 a large isolated rock on the southern shore of the lake, midway 

 between the two islands, to erect a station upon it: thence I de- 

 signed to accompany Lieutenant Gunnison to town, and fit out a 

 party, to be placed under his command, for the survey of the east- 

 ern shore of the lake, as well as of that part of the valley lying 

 between it and the foot of the Wahsatch range. It rained and 

 snowed several times in the course of the morning, and the day 

 was very cold and unpleasant. We erected the station upon a pro- 



