THE TOPOGRAPHIC SURVEY OF MICHIGAN. 163 



important work was done in order to furnisli satisfactory base-maps for 

 use in niakin<»; detailed studies, particularly of llie ,u('ol()<»y of the iron 

 bearing- roeks. \'ery complete and accurate reports on these iuvestijia- 

 tions have been i)ublislied, accomjianied by both top<)graj)hic and geologic 

 maps without cost to the State of Michigan.* 



CO-OPERATIVE T()l'0(a;Al'lllC SUKVEVS IN .MlCllKJAX. 



In 1901 and 1!M)2 a topographic survey was made by the United States 

 Geological Survey, in co-operation Avith the Geological Survey of Michigan, 

 of an area of 910 square miles, in the Southern Peninsula of Michigan, 

 and including the region about Ann Arbor. Ypsilanti, etc. The 

 work was done under the immediate direction of Mr. Robert Muldrow, 

 to whose skill and efficiency much credit is due from the citizens of this 

 State. The map on which the results of this work are shown, is termed 

 a thirty-minute sheet, that is, it includes one-half a degree of latitude 

 and onedialf a degree of longitude, is drawn to scale of about two miles 

 to one inch or ttsVoit of nature, with 20-foot contour'intervals. It is 

 to be printed in three colors, uniform with the other sheet of the "Tono: 

 graphic Atlas of the United States," and designed at the Ann Arbor 

 quadrangle. In addition to the map now in hand, bench-marks, giving 

 the precise elevation above the sea, have been placed at many convenient 

 localities throughout the region it represents; these will be of assist- 

 ance in making local detailed surveys for various purposes, and serve 

 to unite in one system all surveys based on thejn. 



The expense for field work for the map just described, was |0,4S2.47, 

 and for office work in pre})aring the data for publication, about flOO.OO; 

 making the total cost approximately |G,880.00. Of this sum |2,000.00 

 was paid from the approj)riation made by the State Legislature, for the 

 Geological Survey of Michigan, and the remainder by the United States 

 Geological Survey. The total cost ])er square mile was about $7.55, or a 

 triHe over one cent per acre. The State of ]Michigan is entitled to have 

 a reproduction made of the original copper plate from which the map 

 is to be printed, if it so desires, or as is the rule with all publications 

 issued by the Federal government, may order as many prints from the 

 original plate as is required, at the cost of press work and paper. In- 

 dividual copies of the Ann Arbor quadrangle will be sold by the United 

 States Geological Survey at five cents each ; and may be obtained in num- 

 bers exceeding 100 for two cents per sheet. 



The map now com])leted of the region about Ann Arbor and Ypsi- 

 lanti, is an admirable piece of cartograi)hic work, and one foi' which the- 

 citizens of that region should be very grateful. Its accuracy and value 

 have been recognized by all com])etent judges who hnve examined it. In 

 this connection I am permitted to make ]»ublic the following testi- 

 monials : 



M. S. ^V. Jefferson, Professor of Geography in the Normal College 

 at Ypsilanti, writes : 



"The ma|) of the Ann Arbor quadrangle is to the students of gebg- 



* The Marquette iron-bearing district of Michigan, witli atlas. Ijy Cliarh-s Richard Van 

 HiS(> and William Shirley Bayley, including a chapter on the Kcitulilic Trnngh by Henry 

 I>loyd Smith, Washington. D. C., Government Printing Office. 1.S!»T. ([uarto, pages I-XXVI, 

 1-tiCfs, and folio atlas of :{!• sheets. I'rice $'(."."1. 



(geological Atlas of the T'nited States, Menominee special folio. Michigan. Folio No. 62, 

 by ('. R. Van Hise and W. S. Bayley. Size 18 by 21 inches. l."> pjigcs of text ; one topo- 

 grai)hic nnd one geologic map. Price -5 cents. 



