NO. I CAMBRIAN FAUNAS OF EASTERN ASIA 4^ 



tologic horizons of the Ch'ang-hia area are recognized here with ease. The 

 black oolite is much reduced in thickness, and is largely replaced by shales. 

 The Ku-shan shale is thicker and carries fossils which belong to the Ch'ang- 

 hia and Ch'au-mi-tien formations, respectively, in its upper and lower por- 

 tions. The Qi'au-mi-tien limestone alone retains the general character noted 

 in the first area studied, but its base is somewhat shifted. Thus, the Kiu-lung, 

 which in the Ch'ang-hia district is a group composed of three formations, 

 is in the Sin-t'ai district a consistent formation, containing members of 

 limestone and shale, which are of local occurrence only.^ 



RELATION OF THE CAMBRIAN TO THE ORDOVICIAN 



The Ch'au-mi-tien limestone is described by Blackwelder as a very 

 dark gray, finely crystalline rock that has a distinctly blue color 

 where exposed to the weather. The summit of the formation is 

 marked by a change in the character of the sediments, the lower 

 member of the next younger series being yellowish in color and 

 notably dolomitic.^ 



The Tsi-nan formation above the Cambrian is one of the most 

 widely distributed formations in China and is readily recognized by 

 the light-colored argillaceous limestones or dolomites and thin 

 shales of its lower member and the brown dolomitic limestone of its 

 upper member.^ 



The Tsi-nan formation is referred to the Ordovician on the evi- 

 dence of fossils found in its upper member. No fossils were found 

 in the lower portion." 



The transition from the Upper Cambrian to the Tsi-nan forma- 

 tion is not marked by an unconformity, but the introduction of argil- 

 laceous and dolomitic limestones indicates a change in sedimentation 

 that was brought about by diastrophic action that revived erosion 

 and ultimately led to the great epeirogenic changes that marked the 

 close of the Sinian. The fauna of the Cambrian disappeared, so far 

 as known, everywhere in the western Pacific Province and the 

 faunas of Ozarkian " and Canadian time did not flourish in the Tsi- 

 nan sea, and apparently entered it only at rare intervals. It may be 

 that faunas corresponding to the Lake Champlain and Mississippi 



^ Blackwelder, Eliot. Research in China, Pub. No. 54, Carnegie Institution 

 of Washington, Vol. i, Pt. i, 1907, Stratigraphy of Shan-tung, pp. 2)6-2,7- 



' Idem, pp. 34, 35. 



^ Idem, p. 44. 



* Idem, pp. 44-46. 



^Ulrich, E. O. Bull. Geol. Soc. America, \'ol. 22, 1911, Revision of the 

 Paleozoic systems, p. 627. 



