46o E. K. SOPER 



light buildings of any description, it is not necessary to have a 

 perfectly rigid foundation. The drift throughout Minneapolis is 

 usually fairly solid at moderate depths below the surface and is 

 quite safe for foundations for buildings of average size. But in the 

 regions along the courses of the buried river valleys, where the drift 

 may be from loo to 250 feet deep, areas of loose sand which often 

 has a tendency to run are frequently encountered. In such 

 localities it has been found necessary to use piling in constructing 

 foundations for large buildings. 



The main business section of the city lies back from the buried 

 valley and in the downtown district the average distance to bed- 

 rock is only 2 5 to 30 feet. The rock in this locality consists of lime- 

 stone or hard shale and can easily be reached if necessary in building 

 operations. For this reason it has been necessary to use piling in 

 the construction of only a few buildings in the city. Should the 

 zone of large buildings north of Hennepin Avenue be extended in 

 the future a few blocks farther west beyond the Great Northern 

 Railroad tracks, it will be found necessary to use piling, caissons, 

 or some type of foundation adapted to soft ground, for many if not 

 all of the large structures. The side of the buried valley in this 

 vicinity drops off rapidly, so that points along the present channel 

 of Bassett's Creek overlie the very bottom of the old valley nearly 

 200 feet below. Much of the material filling the old gorge in this 

 vicinity is loose sand. At all points in the city, except those along 

 the sides and courses of the buried valleys, the foundations are 

 generally good. 



