226 E. B. 15KANS0N ORIGIN OF RED REDS OF WESTERN WYOMING 



1. Lakes must have depths of hundreds of feet to prevent concentra- 

 tion to point of precipitation for salt. 



2. Conditions of drainage basin, part 1 : (a) Eelatively flat sandstone 

 area 30,000 square miles in extent; (h) rainfall, 10 inches; (c) nin- 

 off, 10 per cent; (d) 50 parts per million calcium sulphate in the run-off 

 waters. Enough calcium sulphate brought in each year to make a layer 

 .000075 inch thick. 



3. Conditions of drainage basin, part 2: (a) Highlands area of -13,000 

 square miles; (h) rainfall, 15 inches per year; (c) run-off, 10 inches 

 per year; (d) 10 parts calcium sulphate per million in inflowing waters. 

 Enough calcium sulphate brought in each year to make a layer .000221: 

 of an inch thick over the receiving basin. 



Total calcium sulphate brought in each year about .0003 of an iucli, 

 and about 40,000 years required to bring in 1 foot. Evaporation required 

 over the receiving basin, 58 inches per year. 



Assumptions for 10-foot gypsum deposits over 2,000 square miles: 



1. Basins must have a depth of hundreds of feet to prevent dry 

 seasons from bringing water to point of saturation for salt. 



2. Conditions for drainage basin, part 1 : (a) Relatively flat sandstone 

 area 38,000 square miles in extent; (h) i-ainfall. 10 inches per year; 

 {<■) run-off, 10 per cent; (d) 50 parts calcium sulphate brought in each 

 year to make a deposit .000475 iuoli thick ovei- the 2.000 square mile 

 basin. 



3. Conditions for drainage basin, part 2 : (a) Highlands of 43,000 

 square miles: (/)) rainfall, 15 inches; (r) run-off', 10 per cent; (//) 50 

 parts per million calcium sulphate. ( A lower run-off and higher calcium 

 sulphate content assumed because the mountain streams now flow for 

 some distance over the arid plains.) 



Enough calcium sulphate brought in each year to make a deposit 

 .0008 inch thick over the 2,000 square mile basin. 



Total of .001275 iuc-li of gypsum per year, x^bout 85,000 3'ears re- 

 quired to get 9 feet of gypsum. 



Sixty-one inclies of water per year over the entire surface of tlie basins 

 must be evaporat<'(l on the above assumptions. 



("OVDITIOXS XOT EXPLAIXEI) HY TIIR HYPOTHESIS ' 

 WHAT BECAME OF THE CALCIUM CARBONATE* 



As previously stated, the carbonates are nearly as abundant in the 

 sTreani waters as the sulphates. Calcium carbonate would be in practi- 



