GEOLOGICAL SUEVEY OF THE TEREITOEIES. 441 



section Lave been worked oat witli the degree of precision attainable 

 by instrumental observation, the main object in coustructing" it being 

 merely to illustrate approximately the position and vertical range ot' 

 tossils with relation to the coal-beds, and to give a general idea of the 

 lithological characters of the series. It should be stated, however, that 

 the dip and estimated distance across the strike of the strata would 

 indicate even a greater thickness than the sum of the individual beds 

 observed. 



The dip of the beds, including the main coal (5) toward the lower 

 part of the section, seemed not to differ much from about 8° to 10° below 

 the horizon, to the northwestward ; but it increases gradual!}^ in that 

 direction, so that at the fourth ridge it is about 25°. Between this 

 ridge and the mouth of the caiion we observed no marked change ot 

 dip, though there appeared to be a slight uueonformability between the 

 conglomerate and the lighter colored beds below at this place; and this 

 unconformity is more obvious at other points near here ; v/hile farther 

 up, near the head of the caiion, it is very strongly ouirked, the discord- 

 ance being, according to Mr. Emmons, as much as 25°. 



Unfortunately, we have riO means of ascertaining the precise distance 

 by an air-line traversed by the section, the linear survey of the Coal- 

 ville township not yet being completed. If we estimate the distance at 

 three miles, and the mean dip at 17°, however, it would give a thick- 

 ness not materially greater than the aggregate of beds noted in the 

 section. If the distance should be as much as three and a half to four 

 miles, however, the difference would be so great as to warrant the con- 

 clusion that we have overestimated the dip, or, what is much more 

 probable, underestimated the breadth of some of the valleys between 

 the ridges, and consequently the thickness of strata hidden beneath the 

 same. As evidences of horizontal displacements of some of the ridges, 

 however, were observed, it is possible that the discrepancy may be, in 

 part at least, accounted for in that way.* 



Mr. Emmons gives in Mr. King's report about 6,000 feet as the entire 

 thickness of the Cretaceous series here, exclusive of the Echo Caiion 

 conglomerate, which is apparently Tertiary. But I infer that he includes 

 in this estimate a considerable thickness of lower strata farther up 

 Weber Eiver than our examinations extended. 



All of the lower beds forming divisions 1 to 6, inclusive, of this section 

 are seen in a low hill, or rising space, directly on the southeastern mar- 

 gin of Coalville, flexed around so as not to conform to the general dip 

 and strike of the strata between this vicinity and Echo Caiion ; their 

 strike being nearly north and south, and their dip nearly westward, 

 some 14° below the horizon. About two miles to the northeastward, 

 however, and at a higher elevation, coal-mines have been opened on the 

 main bed forming Iso. 5 of the section, that show this bed and the over- 

 lying sandstone and other strata, conforming there with the general dip 

 and strike of the beds between there and Echo Caiion. Between these 

 mines and Coalville, the highly fossiliferous strata forming the division 

 aSo. 3, which we know properly holds a jDosition below the main coal- 

 bed, occur some hundreds of feet north of a right line between these 

 mines and the coal-mine directly at Coalville, in the same bed; thus 



* Along Grass Creek Tve observed some curious indications of lateral displacements. 

 This creek cuts very obliquely through some of the ridges, which do not correspond on 

 opposite sides. That is, the ends of the ridges on opposite sides of the creek do not 

 coincide exactly, those on one side ending opposite intervening valleys between those 

 on the other, as if there had been a fracture along the course of the creek, aud a lateral 

 displacement of the strata on one or both sides of the same. 



