ART. 14 MICHIGAN TRAVEESE GROUP POHL. 7 



The establishment of an almost unbroken series of depositional 

 details from the basal exposed Traverse beds to the overlying 

 Waverlian is one of the innovations of the present research, and 

 in view of its initiation here it is desirable to present the details on 

 which the conclusions are founded. For the illustration of the dis- 

 cussion immediately following the reader is referred to Plates 1 and 

 2, on which evidence and results are graphically represented. 



In this presentation the normal method of investigation will be 

 followed and the localities will thus become numerically disarranged 

 when their sections are correlated so as to give a continuous succes- 

 sion from older to younger beds. Field determinations of lithologic 

 " beds " and f aunal " zones " are here retained, for they have both 

 usually been found to be consistent over the area under discussion. 

 The fossils particularly, although they may and often do have a 

 greater geological range than is suggested by the places mentioned 

 for them, are there especially abundant and serve as useful handles 

 to characterize individual portions of the section. 



The ojidest known strata of Middle Devonian age in the western 

 Lower Peninsula are exposed in a series of undulating ledges and 

 low bluffs at water level on and south of Gravel Point, II/2 miles 

 west of Charlevoix. The beds in this vicinity have a slight, gen- 

 erally southeastern dip. This general dip is, however, entirely 

 regional, for the jlocal structure is verj'- complex. The entire region 

 is underlain by more or less elevated domes and local anticlines and 

 synclines which have an entire lack of consistent trend. The base of 

 the section is to be seen in such a dome about one-eighth of a mile 

 south of Gravel Point almost at water Jievel. The sequence is then 

 easily followed northeastward across the beach where the beds dip 

 almost eastward to a low bluff which has been faced by a small 

 quarry. The highest bed is found at Gravel Point in a small syncline 

 or basin. Various zones of the section are excellently exhibited 

 by reappearance at the surface along the shore the entire distance 

 from Gravel Point to about a mile southward. The section exposed 

 here in downward succession is as follows. 



Oeological section at Gravel Point (localities 8 and 8a) 



Gravel Point stage. 



Zone 4- — Light brown, cryptocrystalline, extremely massive, pure limestone 

 with a conchoidal fracture, breaking easily in all directions into small 

 fragments with sharp edges. In appearance like lithographic limestone, 

 with no semblance of bedding planes. The fauna is not abundant but 

 is quite varied, comprising a dumose Favosites, a small digitate Fa/vo- 

 sites, a distantly mammillated Stromatopora, small Athyris, large 

 Craspedophyllum, costate Stropheodonta, and Prismatophyllum. A dark 

 gray shale at the top carries abundant small Stropheodontas in particular. 

 Thickness exposed 2 feet 6 inches. 



