18 J. H. Kloos—Cretaceous Basin in the Sauk Valley. 
Trenton limestone take the place of Potsdam and Calciferous, 
continuing to St. Paul and St. Anthon 
mation.* I have not yet succeeded in finding the crystalline 
limestones of the Canadian Laurentian, though at several places 
west of the Mississippi I have met with large limestone boulders, 
which I refer to this period. At St. Cloud, Sauk Rapids and 
Watab on the Mississippi, the rocks of the Laurentian ridges are 
quarried and are commencing to be used extensively for fronts 
of large blocks and government buildings at St. Paul, Chicago 
and even in cities lower down the Mississippi Valley. Some of — 
the syenitic and dioritic varieties form a splendid material for — 
ornamental work and monuments. 
Leaving the Mississippi at St. Cloud and going westward up 
the Sauk Valley, we cross the belt of Laurentian rocks at right 
angles, and remain among the low granitic hills for 25 miles. 
There is no continuous ridge or uplift; at several places we 
find ledges of granite, syenite, granitoporphyry, hypersthevite 
and diorite, either exposed at the water’s edge or cropping out 
e€ prairie. e river, however, has not cut deep enough © 
into the solid rock to show the continuance of the ledges, and 
the glaciers and icebergs of the erratic period have swept over 
* Sauk Centre, 40 miles west of the Mississippi, is the only place where I found 
ee agg of gran to have a somewhat gneissoid odurdinced Tt is here associated — 
a 
