Mar., 1910.] Pennsylvanian Limestones. n 



J 



section without allowance for dip. Three of the five Hmestones 

 are so far accounted for at elevations as follows: 1015, 1043, 

 and 1069 above sea. Those at Best's Station are to be added, 

 but being 2 miles away dip must be considered. The nearest 

 point for comparison of elevations of all five limestones is at 

 Alliance. The outcrops at Best's Station are about 4^ miles 

 from Alhance and those about North Benton about 7 miles, 

 except the Howenstein outcrop which is about 65. Comparing 

 the elevations of the lower three at the two places, they are as 

 follows: 



Alliance Xorth Benton Difference 



Howenstein. 1008 1069 61 



Upper Mercer 966 104:i 77 



Lower Mercer 945 1015 70 



It appears at once that there is a dip toward Alliance from 

 North Benton whatever it may be in any other direction. For 

 the Mercer limestones it is 10 and 11 feet per mile, for the How- 

 enstein a little over 9 feet per mile. It will be remembered, how- 

 ever, that the latter stratum lies relatively higher at Alliance 

 than in the Nimishillen valley. Comparing the upper two 

 limestones likewise they appear as follows: 



Alliance Best's Difference 



Vanport 1081 1101 20 



Putnam Hill 10;52 10S4 52 



The first difference is not what would be expected from the 

 dip found in the first three limestones, but the second corresponds 

 very well giving a dip of about IH feet per mile. The Vanport 

 clearly lies considerably lower relatively than at ony other place 

 found, and its dip of less than 5 feet per mile is not representative 

 of the general dip of the strata. Therefore in combining the out- 

 crops at Best's and Benton a general dip of about 11 feet per 

 mile must be used in adjusting the interval between the Howen- 

 stein and Putnam Hill limestones, and combining the outcrops 

 for a section at North Benton the following elevations represent 

 the horizons of the several limestones: 



Vanport 1 125 



Putnam Hill 1 106 



Howenstein 1069 



Upper Mercer 1043 



Lower Mercer 1015 



It will be observed at once that the elevation of 1125 for the 

 Vanport does not conform to the 11 foot dip, but it is quite prob- 

 able that it lies at about 1125 at this point since it lies only 17 

 feet above the Putnam Hill at Best's Station, which strongly 

 suggests a thinning of intermediate strata in this region. It is 

 true that the interval between the Lower Mercer and the Van- 

 port would thus be only 110 feet, while the same interval at 



