ECOLOGICAL CROSS SECTION OF THE MISSISSIPPI 



141 



TABLE I. 



SECTION. 



Feet. 



Thick- 

 ness. 



Depth 



Dirt • 



Gray sand ^ '/ " -i " i ' * ** i * ' ' * 



Very coarse sand, grains of various rock as li glacial ma- 

 terial , V ' ' n' ' * 



Coarse sand and gravel pebbles of brown and yellow 

 quartzite, greenstone, etc., shells, fragments 



Black clay, almost non-calcareous 



Limestone fragments, may be mixed shale and clay 



Gray, non-calcareous shale 



Light black, clay or shale, non-calcareous 



Same laminated, gray and white 



Gray limestone churned to a very fine sand ............ 



Gray, very siliceous limestone, possibly chert, but looks 

 like sand grains; comes in large fragments 



Very fine white to gray sandstone, almost non-calcareous 



Light colored limestone, churned to very fine sand 



Light sandstone, very fine ■ 



Dense white limestone 



Darker limestone 



Light limestone, dense 



Very ferruginous limestone 



Very ferruginous limestone, cherty 

 Dense gray limestone 



Lighter limestone 



Gray limestone 



Darker limestone 



Limestone and chert, very ferruginous 



Limestone less ferruginous V ' ' \ 



Limestone less ferruginous, finely powdered 



Limestone less ferruginous, some chert 



Limestone, largely chert, crinoid stems 



Dark gray limestone 



Mostly white chert. .li."V-' {,1 



Light colored limestone, often stuck together with light 

 colored clay which may have been largely washed out 



Blue calcareous clay 



Gray cherty limestone 



Nearly all white chert, finely powdered but angular 



Limestone and white chert 



Largely white chert, finely powdered but angular 



Largely white chert, finely powdered but angular 



Largely white chert, as fine as glass sand 



Limestone and white chert 



Largely white chert fragments . . 

 White limestone and white chert 



Largely white chert f ra gments 



Greenish gray limestone ;•.••.•,■■ i" ' 



Greenish gray limestone, much chert of similar color 



Pink calcareous clay 



40 

 20 



10 



80 

 55 



5 



5 



5 



5 



5 



5 



65 

 5 

 10 

 45 

 20 

 30 

 10 

 20 

 50 

 15 

 10 

 10 

 10 

 45 

 10 

 35 

 25 

 20 

 10 



38 



62 



10 



10 



10 



30 



10 



20 



10 



15 



55 



15 



30 



20 



30 



40 

 60 



70 



150 

 205 

 210 

 215 

 220 

 225 

 230 



235 



300 



305 



315 



360 



380 



410 



420 



440 



490 



505 



615 



525 



535 



580 



590 



625 



650 



670 



680 



718 



780 

 790 

 800 

 810 

 840 

 850 

 870 

 880 

 895 

 950 

 965 

 995 

 1,015 

 1,045 



BORINGS NEAR MONK's MOUND. 



