MICHIGAN ACADEMY OF SCIENCE. 139 



zoic time, built up by median and later succeeding formations, not unlike 

 saucers laid upon each other, the latest bed rock formation, the Coal Meas- 

 ures, being at a later time relatively elevated, in conformity with the law 

 established by James Hall of the greatest accumulation of sediment? form- 

 ing areas of uplift and consequent highest elevation. In this manner it can 

 be seen that the physiography of iMichigan as seen in its present development 

 has very early geological antecedents. 



AREA AND ELEVATION OF MICHIGAN. PRE-GLACIAL DRAINAGE. 



According to the statement furnished by Mr. H. M. Wilson, Geographer 

 for the U. S. Geological Survey, the area of Michigan is now accepted as 

 57,480 square miles. By planimeter measurement of Plate 11 of Water 

 Supply Paper No. 183, issued by the government, I make the area of the 

 Lower Peninsula 41,452 square miles. Newaygo county was taken as the 

 vmit of comparison and area. Computations based on Farmer's ''Michigan 

 Book" give an area of 16,560 square miles for the Upper Peninsula. By 

 difference I would make this area 16,628 scjuare miles. 



Mr. Henry M. Gannett has issued the fourth edition of his Dictionary 

 of Altitudes, this publication being Bulletin No. 274 issued by the U. S. 

 Geological Survey. An average of 1457 altitudes, the greater part being 

 railroad stations, determined with as much accuracy as possible, gives Mich- 

 igan an average elevation of 840 feet above sea level. Lake Erie is 572 feet 

 above tide and lake Superior 602 feet above the level of the sea. This de- 

 termination is very likely somewhat beloAv the true elevation, but is based 

 upon the only complete information at present available. 



The average elevation of the Lower Peninsula of Michigan is 854 feet above 

 sea level as determined from a 100-foot surface contour map prepared by 

 Frank Leverett and forming Plate II of Water-Supply Paper 183, issued by 

 the U. S. Geological Survey. In making this determination "the first step was 

 to measure, by means of the planimeter, the areas lying between different 

 contours. Then each such area may be assigned an elevation half way 

 between the two limiting contours, and multiplied b}" that number of feet. 

 The sum of these products divided by the area give an approximation of 

 the average height."' 



The percentage of area in Lower Michigan between the different contours 

 is shown in the following table: 



The line of 44° latitude extends from just north of Standish, Arenac 

 county, west to just north of Ludington on the Lake Michigan shore and in- 

 cludes in latitude the northern 5-12 of the state. Within this area is the 

 highest elevation in Lower Michigan. The following percentages apply to. 

 this area: 



1 Communication, Henry Gannett, Feb. 8, 1907. 



