576 METASPERMAE OF TIE MINNESOTA VALLEY. 
till soil is the most promiment in the Minnesota valley and oc- 
curs in both prairie and forest region. It is somewhat more 
fertile than the red till and second as a subsoil only to the al- 
luvium. The fertility of any'soi] is, however, secondary so far 
as concerns the subscil and itis to the layer of loam which 
covers the till that the productive qualities must largely be re- 
ferred. The loam varies in its per cents. of nitrogenous sub- 
stance, but in general maintains a high average. 
Climate. Owing to the short time during which meteorolog- 
ical observations have been made in the valley of the Minneso- 
ta it is not possibic to get all the data that are desirable for an 
explanation 0. its climate. From the statistics compiled for 
the Smithsonian Institution, by Schott, I am able to present 
the following table of mean annual and seasonal precipitation 
at certain pc'nts of interest. 
TABLE OF PRECIPITATION. 
In this table the figures are means arranged from observa- 
tions extending over various periods, The precipitation is 
given in inches and fractions. 
EXTENT 
LAT. | LONG. |ELEV.|SP’NG] SUM. | AUT. |WINT| YEAR. OF 
OBSER’'N 
Ets, Ridgely sce cies tec 44°,30' | 94°.45' | 1230 | 6.48 | 9.11 | 5.86 | 4.02 | 25.47 | 13 years 
Ft, Snelling ............. 44°.53' | 93°.10' | 820 | 6.20 | 10.14 | 6.40 | 2.57 | 25.31 | 38 years 
Lac Qui Parle......... ..| 45°.00' | 95°.30' | 946 | 7.78 | 11.84 | 6.47 | 2.98 | 29.07 | 5 years 
NOW: Tliminissiciscinsy srsistrsbree 44°.00' | 94°.30' | 1007 | 6.55 | 11.38 | 5.49 |] 2.53 | 25.95 | 10 years 
Madeliawe isc i ascraainwian 44°,19' | 94°.30' | 821 | 7.41 | 9.87 | 7.39] 4.21 | 28.88 | 2years 
St. Paw leinss seas sveazeviws 44°,58' | 93°.03' | 693 | 7.81 | 12.14 | 7.09 | 3.01 | 30.05 | 17 years 
At Ft. Snelling the maximum annual precipitation during 
the period was in 1849 when 49.69 inches of water was precipi- 
tated. The minimum wasin 1852 when 15.07 inches was pre 
cipitated. The observations extend from 1837 to 1874. 
At St. Paul the maximum was in 1865 when 38.14 inches fell. 
The minimum was in 1864 when 14.86 inches fell. 
The mean yearly precipitation, as indicated upon the iso- 
hyetal maps prepared by Schott, varies in the Minnesota valley 
from 20 to 82 inches. Itis greatest in the region around Ft. 
Snelling and least in the high land of the western boundary. 
For the spring, summer and autumn the mean precipitation in 
the delta region of the Mississippi is respectively 18 inches, 
and for the same region the winter precipitation is 16 inches, 
1aaking a total mean precipitation of 70 inches. 
