IOWA ACADEMY OF SCIENCES. 181 



by strong individuality in color, and display all shades of 

 gray, brown, red, and yellow, producing effects in the 

 canyons of the Bad Lands that are often exceedingly 

 beautiful. Beds of high grade fire clay which have a 

 fusing point above 3,500^ F., are common. A series 'of 

 clay strata may dip at an angle of ten degrees or more, 

 while those above and below are horizontal. The effect to 

 the eye is not unlike that of cross-bedding. 



The lignite is commonly brown in color and exceedingly 

 woody in structure. Tree trunks many feet long and from 

 one to two feet in diameter are often found lying prone in 

 the lignite bed. Unfortunately the bark is never pre- 

 served or other characteristics by which they can be iden- 

 tified without the microscope, and as yet microscopic 

 studies have not been undertaken. Small masses of a 

 rosinous-like substance are often distributed through the 

 lignite. Leaf prints and delicate forms have not been 

 found in the lignite itself, but in the associated clays they 

 are well preserved. Specimens taken from a clay which 

 lies between two lignite beds in Ward county were sent to 

 the Smithsonian Institution for identification, and were 

 determined to be: 



Sequoia lavgsdoifii (Brongniart) Heer. 

 Sequoia b*evilolia Lesq. 

 Sequoia angustifolia Lesq. 



vSequoia cones, finely fossilized, were found in great 

 abundance in Morton county. Leaf prints of VlJnirnum 

 perfectly preserved in thin bands of clay-ironstone were 

 found at a number of points. 



Unusual opportunities to study the relations of the lig- 

 nite to the under clay are given, since a great deal of min- 

 ing is done by the strip-pit system, which leaves the clay 

 bare and shows exactly the line of contact between clay 

 and coal. The extensive exposures in the bluffs of the Bad 

 Lands are instructive in the same way. The underlying 

 clay is practically free from roots. It may contain limbs 

 or trunks, which are scattered irregularly here and there, 

 but these are not uncommon anj' where in the Laramie 

 clays. In not a single instance was a stump found with 



