CLIMATE AND SOIL. .MinIllesOta lies in the mid dle of the north temperate zone, and in the geographical centre of the continent. This gives it a continental climate, with marked extremes of temperature. The average temperatures for January are 15° F. at the southeastern corner, and at the northwestern corner only I° or 2° F. For July it is 70° F. in the south and 05° F, in the north. Maximum shade tempera tures rise above 100° P. over all the State west of Duluth. while the minima are 40° F. below zero in the smnbern and northeastern counties and 50° F. below in the extreme northwestern, thus giving a range of 150° degrees or over for Red River Valley. The annual rainfall ranges from 20 inches in the northwest to over 3t) inches in the southeast. The rainfall is charac terized by a scant precipitation in the winter season, and moderately heavy rains during the crop season. There is an average annual snow fall of 20 inches in the southwestern part of the State• which increases gradually to SO inches at Pigeon Point. The southern comities have an average annual relative humidity of less than 70 per cent., rising steadily northward to 75 per cent. in the northwestern counties. The average velocity of the wind is 8 miles per hour in the east. and almost 11 miles per hour at Crooks ton. whfch is the highest inland average velocity recorded in America. The average path of the northwest c•yelones passes through the southern counties. Between 300 and 350 smelt storms occur in ten years. The prevailing wind is west in the northern half and southwest in the southern half, The climate on the whole is rigorous in winter, though mild and even occasionally hot in the southern comities ill summer. But the nights are always cool. and the air dry. making the whole State a favorihe summer resort.
The soils of the State are wholly glacial, and since the outcropping stratified rock is largely limestone, most of soil derived from this source is extremely rich—a black and finely comminuted loam. On the older drift in the sofa heast ern count ies, for 3i) to 40 miles back from the Mississippi River. there is a coating of loess, an extremely fine blaek ionnt of great fertility. Whore the Cambrian sandstone outcrops in the cast central part of the State. considerable areas
are covered with a light saltily soil, not at all encouraging for agriculture. In the old land of the nortlwast and north central enmities Mere are large areas almost denuded of soil, or env vrvd with a scanty coating of granitic drift. In the Valley of the PM River the silts of the ex• tinet Lake Agassiz occur, a tine black soil of almost incomparable ri,•lmess, constituting some of the best wheat lands in the world.
t;rot The port lowest ern corner of the State formed zi part of the old Archaean cont inent• and its portion was in Arehasan times occupied by a large island. These areas now consist of granites and gneisses of the archaran basal complex, parts of which have also been un covered along the upper valley of the Minnesota River, where there are valuable granite quarries. Shore deposits and lava flows of the Iluronian age outcrop as highly metamorphosed rocks in Inroad zones along the margins of these Archaean old lands, cutting into the latter in deep tongues and bands, some of .which contain iron-bearing beds of great wealth. The broad linronian belt extending southwestward from the Minnesota River contains the Sioux quartzites, a most beau tiful and valuable building-stime, and beds of metamorphosed red mud. the eatlinite, or far famed red pipestone of the Indians. The Lake Superior synclinal trough is occupied by Cam brian sandstones and limestones, and Ordovician rocks occur in the southeastern part of the State, consisting of the Saint Peter sandstone beds cov ered with Trenton limestone, a combination which has given rise to the bluffs along this part of the _Mississippi, and to the Falls of Saint Anthony. Silurian rocks occur in the valley of the Red River and in some of the southeastern counties, and slight cretaceous deposits are found in va rious parts of the State. The Pleistocene ice in vasion is most largely responsible for the present surface, the State lying in a sort of focus of glacial activity. It was entirely covered by ice in the Kansan and Towan epochs, and in the Wis consin epoch two great lines of invading ice met at the centre of the State, and flowed south in a great tongue into Iowa.