94 The American Geologist. February, i899 
" Mesozoic Stratigraphy in SoutJnveatern Black Hil/s." This 
paper was an account of preliminary studies made during the summer 
of 1898. A detailed account was given of the relations and variations 
of the Mesozoic members. An announcement was made of the dis- 
covery of fossil bones, mainly of very large size, from the Cycad 
horizon in the lower Cretaceous and of an interesting limestone a 
short distance higher in the series. The marine Jurassic was found 
to be abundantly fossiliferous in the area studied. Much new light 
was obtained in regard to the stratigraphy of the Benton, Niobrara 
and Pierre formations, and there was discovered in the latter a 
"Teepee zone" due to calcareous lenses filled with Lucina occidentalis. 
similar to the one described by Gilbert in southeastern Colorado. 
Mention was also made of the discovery of fossils in the Purple lime- 
stone and in the top. of the Minnelusa formation. 
"Relations of Tertiary Formations in the Western Nebraska 
Region." This paper set forth the result of observations 
made in 1896 and 1897. In the western Nebraska region there was 
found an extension of the White River series comprising the Titan- 
otherium sands, to which the name Chadron has been applied, and a 
series of pink clays, designated the Brule formation, which com- 
prises the upper members of the White River series, and probably 
some additional beds discovered in the highlands south of White 
river. Next above and separated by a marked unconformity is a 
series of sand and sandstones called the Gering formation. This is 
overlain by the "Loup Fork" which has been found to comprise a 
lower member, called the Arikaree formation in the Pine Ridge re- 
gion, overlapped to the southward by a considerably younger mem- 
ber, called the Ogallala formation, which extends into Kansas and 
southward as "Tertiary grit" or "mortar beds." The Arikaree and 
Ogallala formations are separated by a strong unconformity, with 
shore deposits. The observations were extended northward into the 
Big Bad Land region in order to give a definite basis to the correla- 
tion. 
"■Shore Line of Tertiary Lakes on the Slopes of the 
Black Hills." These shore lines were found to extend far up the 
.'lopes of the central region of the Black hills. Extensive areas were 
also discovered of the Tertiary formations containing typical mam- 
malian remains of the White River series. In a portion of the area 
the formations are overlain by extensive deposits of Pleistocene sands 
and gravels. From the relations and slopes of the shore lines and 
formations it will be practicable to trace out several stages in the 
uplift and topographic development of the Black hills. 
"The Geology and Physiography of the Lake Region in Central 
America," by Willard Hayes, of the U. S. Geological Sur- 
vey. The region described includes southern Nicaragua and northern 
Costa Rica, extending from 10° 30' to 12° 30' north latitude and from 
the Caribbean to the Pacific. It includes the route of the projected 
