594 THE GLACIAL LAKE AGASSIZ. 



occasionally occupy one, two, or three days, or very rarely a whole week; 

 but on the average, in all seasons of the year, this region has a large 

 majority of clear clays with bright sunshine. 



In addition to the recorded rainfall, seasons that liave a considerable 

 supply of rain, with at least a nioderatel}' humid atmosphere, receive much 

 moisture in the form of the nightly dews, which greatly help the growth 

 of crops; but in seasons of drought, with an arid atmosphere, when all 

 vegetation gasps for moisture, the nights condense little or no dew. 



In winter the snow is connnonly about a foot deep during two or tlu-ee 

 months, from December or January to March. Sometimes it comes earlier 

 or stays later, and very rarely it attains an average depth oi 2 or 3 feet. 

 Nearly every winter has from one to three or four severe storms, called 

 blizzards, in which the snowfall is accompanied by a fierce wind and often 

 by very low temperature. The air is tilled with ilying grains of snow, by 

 which the view to any considerable distance is obscured and the traveler 

 finds his eyes soon blinded in attempting to move or look in the direction 

 from which the storm comes. The earliest snows, which, however, are 

 likely to be soon melted away, usually fall during November, but very 

 rarely they come as early as the middle of September; and the latest snows 

 vary in time from March to May. 



During a series of years of prevailingly copious rainfall and snowfall, 

 extending from 1871 or earlier to 1884, agriculture was partially or gener- 

 ally successful upon a large area reaching westward from the southwestern 

 borders of Lake Agassiz to the Missouri River. Then a series of five pre- 

 vailingly dry years, with long terms of severe drought, extended to 1889, 

 during which the crops of that area were mostly very scanty and for large 

 tracts were several times an utter failure, bringing great distress and dismay 

 to the people, many of whom were compelled to abandon their lands and 

 homes and to remove to more favored portions of the country. A new 

 cycle of plentiful rainfall appears to have begun in 1890, 1891, and 1892, 

 giving again inagnificent harvests in the region from Dennis Lake to Bis- 

 marck aiid southward, which had suffered most severely ijy drought. 



Fluctuations ofJakca and streams. — Through the past hundred years max- 

 imum and minimum stages of the great Laurentiau lakes have alternated 



