724 ABSTRACTS OF PAPERS 



practicallj^ indistinguishable from red beds sediments. The red granites, red 

 porphyries, and other crystallme rocks of the region under discussion con- 

 tributed their share of material to the red beds. Other factors may have 

 entered largely into the formation of the red beds of western Oklahoma. 



Discussion 



Dr. I. C. White: In the Monongahela series of West Virginia we get the 

 same kind of transition from fresh-water limestones to red shales in passing 

 from the northern portion of the State southwestward toward the Great 

 Kanawha River. There are no red beds whatever in the Monongahela series 

 at the northern line of West Virginia, but as the limestones disappear south- 

 westward red shales make their appearance, along with much more sandy 

 material in the shape of gray and brown sandstones. 



ME80Z0IC STRATIGRAPHY OF ALASKA 

 BY G. C. MAETIN 



(Abstract) 



Mesozoic strata cover vast areas in Alaska and constitute a large propor- 

 tion of the thickness of the local stratigraphic column. The recent work of 

 the U. S. Geological Survey has resulted in the accumulation of a great 

 amount of stratigraphic information which is chiefly either unpublished or 

 scattered through reports on local districts or on mineral resources. 



This information is of importance not only because it constitutes so large 

 a proportion of the local geologic facts, but because there are obvious rela- 

 tionships in the Alaskan sections which contribute to a better understanding 

 of horizons in other parts of North America. 



An attempt is made in this paper to summarize all existing information ; 

 to correlate the recognized horizons, not only between different parts of the 

 territory, but with the standard sections in other parts of the world, and to 

 present a pro])osed local classification of the Mesozoic rocks. 



Triassie rocks are widely distributed in Alaska, and include over 5,000 feet 

 of marine sediments containing invertebrate faunas which permit of corre- 

 lation with several well-recognized horizons of the western part of the United 

 States and of Europe. Probably an equal thickness of volcanic rocks is 

 present. 



The Jurassic is well developed throughout much of southern Alaska, and is 

 also present in the Arctic region. The Jurassic rocks are richly fossiliferous. 

 both marine invertebrate and plants being present These faunas and floras, 

 although still largely undescribed, permit of correlation with the standard 

 European sections. Lower, Middle, and Upper Jurassic horizons are recog- 

 nized, the aggregate thickness of the fossiliferous Jurassic rocks exceeding 

 10.000 feet. 



Both Lower and Upper Cretaceous rocks have been recognized in all of the 

 larger geographic subdivisions of the territory, the aggregate thickness of the 

 beds being many thousand feet. The rx)wer Cretaceous rocks are chiefly 

 marine and contain faunas allied to those of Russia. The Upper Cretaceous 

 rocks include fossiliferous marine sediments in which the Indo-Pacific fauna 



