14 FIELD OPERATIONS OF THE BUREAU OF SOILS, 1916. 



BOILS. 



According to available geological data,* Anoka County lies within 

 an area of surface exposures of what are termed young gray glacial 

 drift, red glacial drift, deep wind-laid sand, and glacial-river terrace 

 material washed from both of the glacial-drift sheets, but mainly 

 from the young gray drift. The entire county is apparently under- 

 lain by a relatively thick sheet of red glacial drift, which is overlain 

 more or less completely by a relatively thin sheet of young gray 

 glacial till. Overlying this is the extensive outwash-plain and dune- 

 sand mantle. Within the areas of glacial-drift exposure as well as 

 in the sand-plain area there occur many depressions of various sizes 

 and depths. These are largely filled with peaty accumulations. 



Approximately 4.8 per cent of the county is covered by the well- 

 defined gray drift. This is exposed only in the southeastern part 

 of the county, where it occupies the southeastern parts of Columbus, 

 Centerville, and Fridley Townships. It occurs mostly as a low, 

 rather level till plain, which becomes hilly in a few places. The soils 

 derived from this material are characterized by more or less cal- 

 careous,^ clay subsoils, and are classed in the Miami series. 



The red glacial drift is exposed in the northwestern part of the 

 county, covering most of Burns Township and part of western St. 

 Francis Township. It occupies approximately 9.1 per cent of the 

 county. The greater part of the area covered by this material has 

 a nearly level to gently rolling surface and the soils are classed in 

 the Gloucester series. In the extreme northwestern corner of the 

 county a rather hilly, morainic topography is developed. The soils 

 here are classed in the Hinckley series. Both the Gloucester and 

 Hinckley series have subsoils of varying clay content, and are non- 

 calcareous, although in many places the drift is underlain, apparently 

 at depths varying from 4 to 8 feet, by calcareous material. 



The remaining uplands or about 52 per cent of the area of the 

 coun.ty is occupied by sandy soils consisting of glacial river-terrace 

 materials washed mainly from the gray drift and sands derived from 

 the same material and deposited by the wind over terraces and out- 

 wash plains. This water-laid deposit is of considerable thickness in 

 most places. It is noncalcareous, at least in the upper 3 to 10 feet, and 

 is of sandy texture throughout. The surface varies from quite 

 level to gently rolling, and in places has the character of sand dunes. 

 This deep sandy area is occupied largely by the Merrimac soils. 

 Relatively small areas are classed in the Buckner and Hinckley 

 series. 



1 See Minneapolis-St. Paul Folio, Minn. ; also Leverette sketch map of soil material for 

 Minnesota. 



* This term is used when the material contains enough lime carbonate to cause distinct 

 effervescence in hydrochloric acid. It has no reference to the occurrence of lime in com- 

 pounds other than carbonates. 



