HIMZIJ, GEOLOGY OF WASATCH MOUNTAINS, UTAH 115 



Caninea cylindrica Scouler 

 Spirifer striatiformis Meek 

 Dielasma attemiatum Martin 

 Seminula suhtilita 

 Spirifer rockymontan us 

 Productiis semireticulatus 

 Phyllipsia cf. triniicleata Herrick 

 Ani plexus sp. 

 Orbiculoidea newherryi 

 Spirifer sp. nov. 



Caninea cylindrica is a well-known European species and so far as the 

 writer is aware has not been recognized before in America. It is char- 

 acteristic of the middle part of the Lower Carboniferous in Belgium and 

 the region about Bristol, England. Probably next in importance is 

 Spirifer striatiformis which is very abundant in the Cottonwood region. 

 It likewise points to the Middle Mississippian. 



By far, the most abundant form is the great coral Caninea. The in- 

 dividuals lie closely packed together in a layer about three feet thick, 

 being very firmly cemented together with a siliceous clay which has be- 

 come exceedingly hard. They were discovered by the writer in the early 

 part of the season, and it was thought that they would make an easily 

 recognizable reference horizon on account of their abundance and size, 

 but while their general position was located in many places, no other 

 occurrence was found. 



Immediately overlying this coral bed is the basal Pennsylvanian con- 

 glomerate made up of rounded chert pebbles and silicified corals together 

 with much fine material. This erosion surface truncates the lower beds, 

 as may be inferred by the absence of the coral layer in all other places 

 within the district except the one in which these interesting forms were 

 first discovered near the mouth of South Fork. Careful observation 

 seems to indicate some difference of dip between the upper quartzite 

 beds and the lower limestones. The relation, therefore, is one of low 

 angular unconformity. 



Unconformity between the Mississippian and Pennsylvanian 



There can be no doubt that there exists an unconformity at the top 

 of the Mississippian in the Cottonwood section. The occurrence of a 

 similar break farther to the north has also been reported by Blackwelder^* 

 at the base of the Morgan formation. He says : "The lower limit of the 

 formation (Morgan) is sharp, for the earthy red sandstones rest upon 



2* Op. cit.. pp. 529-530. 



