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The borders between gravel plains and till plains are usually traced by noting either a change in topography or change in vegetation, supplemented, of course, by such exposures as are to be found.

It is the writer's custom to record data successively as collected in the field without attempt to put them under separate subjects, for much time is ordinarily lost and much inconvenience experienced in making such a separation or grouping while on the trail, especially if it is through fields or brush. At the close of each day an index of the main features observed is entered on the fly-leaf of the notebook, so that when the notebook is filled one has an abstract of the notes contained therein. Then at the close of the field season, the areas and subjects embraced in each note-book are put in a catalogue of the notebooks. By this method the writer is able in five minutes time to find any item entered in any of the 250 notebooks he has filled since he began field work. On the field maps marginal references are frequently made to the notebooks which contain the principal geologic data, and as much data as can conveniently be placed on the map is entered there as well as in the notebooks.

In the writer's practice mapping in the field is by a system of colors supplemented to some extent by conventions. The colors adopted have been such as to make strong topographic features stand out prominently, while plains are represented in duller colors. Several of the glacialists have come to adopt the same system of colors and this is a great advantage in reading each other's maps. This system has been elaborated sufficiently to bring out drift structure as well as topography. For example, for topography a moraine is given a red color, an outwash gravel plain a brown color, and a till plain a blue color, while for structure the gravelly part of a moraine has a brown color rubbed over the red, while the clayey part has a blue color over the red. One can thus read from the map the change from clayey to gravelly moraine in the absence of notes of any sort on the map.

Inasmuch as flowing wells are of high economic value, the field maps are made to show areas in which they may be obtained. Marl, peat, and other features when thought to be of commercial value are indicated on the maps and notes are made as to the value of certain classes of soil for certain products, and so forth. Rock outcrops, glacial striae, the course of buried channels, and other features of importance are also noted on the map.

It is the writer's habit to enter in the notebook a brief running description of features noted rather than a mere jotting down of data sufficient to call up the situation. This has been found necessary, not only to render the notebooks intelligible to others, but to insure a correct personal understanding after the lapse of years when the memory can no longer recall the full situation.

Observation needs to be carried along so many lines in the present-day glacial investigations that it is becoming difficult for a beginner to take up the work, and there is a tendency to restrict himself to lines for which he has a special aptitude. One man may be best in mapping moraines and other topographic features but not able to satisfactorily interpret differences in the rock constituents of superposed drift sheets. Another may be quick to see differences in rocks but not in topography. Neither of them may be able to use the criteria from vegetation successfully in the absence of natural exposures. It is also found necessary at times to make maps of important topographic features, so that a man with some engineering skill becomes a valuable member of the field force. These facts and the fact that the beginner is encouraged to keep up the work if he realizes he has an aptitude for it, makes it of some consequence in arranging a field party to select men of various tastes and capabilities, especially if a wide range of phenomena are open to study.

It is doubtful whether any line of geologic investigation requires more constant exercise of both the observational and the imaginative faculties of the mind than the mapping of glacial features. The great areas involved in the broader elements of the interpretation also require long continued holding in abeyance of final conclusions. In the writer's experience there are subjects that have been held tentatively for years, some that are still held tentatively after over a quarter century of study, because the field studied is not yet wide enough to clear up their history and relations.

PROGRESS OF THE TOPOGRAPHIC SURVEY IN MICHIGAN.

An Abstract from the "Biennial Report of the Director of the Geological

and Biological Survey of Michigan."

MR. R. C. ALLEN, DIRECTOR.

The ultimate aim of the topographical survey is the mapping of the entire area of the state, 57,980 square miles, in units of 15' of latitude and 15' of longitude, each unit being issued as a separate sheet on a scale of 1:62500, with a vertical contour interval of twenty feet, except for special areas such as state forests, state military reservations, certain mining districts, etc., where for special reasons a small vertical interval and a larger scale may be more desirable. The topographic mapping of Michigan is contributory to the completion of a topographic map of the entire United States and its dependencies. More than two-fifths of the entire country is now topographically mapped.

The work is being carried forward from year to year by the U. S. Geological Survey largely in co-operation with the various states. Cooperation in topographic mapping with the United States Survey was commenced in the state of Michigan in 1901, when an allotment for such work was made by the director of the U. S. Survey. Up to June 30, 1911, there has been mapped 5,117 square miles in the state of Michigan, this being about 9% of the entire area of the state. Of this 3,530 square miles are located in the southern part of the state. The resultant maps of this area published on a scale of 1:62,500 were made under the topographic standards now in force and are in such detail as to satisfy the engineering, geologic, and economic needs of this portion of the state. Much of the area mapped in the Northern Peninsula is classified as reconnaissance on the maps of that country with the exception of the Marquette, Calumet Special and Menominee Special sheets.

Practically all the quadrangles in the Southern Peninsula were surveyed through co-operative arrangement between the Federal Survey and the Geological Survey of Michigan, but the amount of such co-operation has been small on each side and only sufficient to complete little more than one quadrangle a year.

USEFULNESS OF TOPOGRAPHICAL MAPS. More than two-fifths of the area of the United States is already topographically mapped. In five states the topographic map is completed, in six others over 70% is finished, five have mapped between 50% and 65%, five between 40% and 50%, and eight between 30% and 40% of their areas. Topographic maps of every state in the union are being made. It is not to be supposed that governments would engage continuously in work of this nature were the results not generally regarded as useful, but in order to answer in some detail the question "Of what use are topographic maps?" there is given below some of the main uses which are being made of these maps.

1. As preliminary maps for planning extensive irrigation and drainage projects, showing areas of catchment for water supply, location of water brine, oil and gas wells, sites for reservoirs, route of canals, etc.

2. For laying out highways, electric roads, railroads, aqueducts, and sewage systems, thus saving the cost of preliminary surveys.

3. For improving rivers and smaller waterways.

4. In determining and classifying water resources, both surface and underground.

5. In the problem of the most feasible and economical selection of water supply for cities.

6. In making plans for the disposal of city sewage, garbage, etc.

7. In determining routes, mileage, location of road building material, and topography in country traversed by public highways.

8. In selecting the best routes for automobiling tours and inter-city runs.

9. As guide inaps for prospectors and others travelling through little known regions.

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10. As bases for the compilation of maps showing the extent and character of forest and grazing lands.

In classifying lands and plotting the nature and description of soils.

12. In compiling maps in connection with the survey and sale of lands.

13. In making investigations for the improvement of plant nad animal industries, and in a comprehensive study of physical and biological conditions in connection with the stocking of interior water with good fish and the locating of fish culture stations.

14. In locating and mapping the boundries of life and crop zones, and in mapping the geographic distribution of plants and animals.

15. In plotting the distribution and spread of injurious insects and germs.

16. As a base map for plotting of information relative to the geology and mineral resorces of the country.

17. In manceuvers of the national guard, in the development of military problems and the selection of routes for road marches or strategical movements of the troops, particularly of artillery or cavalry.

18. In connection with questions relating to state, county and town boundaries.

19. As a means of promoting an exact knowledge of the country and serving teachers and pupils in geographic studies.

20. As base maps for the graphic representation of all facts relating to population, industries, and products and other statistical information.

In connection with legislation involving the granting of charters, rights, etc., when a physical knowledge of the country may be desirable or necessary.

SOME COMPARISONS. It was stated above that only 9% of the area of Michigan has been topographically mapped. The percentage for the entire country exceeds forty. We are thus about 31% behind the country at large. Of the 48 states in the union Michigan ranks forty-forth in the percentage of area surveyed. That Michigan has fallen so far behind is mainly due to her failure to take fuller advantage of the plan of co-operation offered by the Federal government. The Federal Survey offers to meet dollar for dollar, up to a reasonable limit, any appropriation the various states may make for topographic mapping. Many states have taken full advantage of this offer and others have even gone farther and have offered more money than the Federal government could meet. In comparison with the neighboring state of Ohio, for instance, Michigan allotments for co-operation seem insignificant. (Ohio state appropriation for 1911-12 was $25,000, Federal appropriation for Ohio for 1910-11, $15,000; Michigan state appropriation for 1910-11 was $2,000, and the Federal appropriation for Michigan was $2.000). The results of the liberal policy in Ohio are apparent when one

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realizes that the entire area of the state will be covered by modern topographic maps within the next four or five years and that more than 70% of the state has been completely mapped.

DOES MICHIGAN NEED A TOPOGRAPHIC MAP?

I have enumerated 21 uses which are made of topographic maps. There are other uses which are not mentioned. Each of these constitute a reason why there should be a topographic map of Michigan. But appeal should be stronger in Michigan than in many other states. Large areas in the northern part of this state await development. Is it not obvious that a good map is the very best aid to the development and settlement of any region? Appeals for maps are made to this department every day in the year, more than half of them from sources outside the state. But we have to face the fact that no accurate maps of 90% of our area have ever been made.

Now suppose the state were in a position to furnish to each of the thousands of home seekers who make inquiry in Michigan each year, maps at five cents per copy showing the exact character of the surface of the country of which inquiry is made,—the “lay of the land" shown more accurately than any photograph could show it,--and suppose there were shown on the same map or other maps the general character of the soils,—would not such inforination return to the state in dollars and cents many times the cost of providing it?

Such maps are not only essential to the home seeker but in every legitimate purpose of development. I say legitimate purpose for the reason that there have been and are now being perpetrated schemes of so-called “development" of lands in the state which are conceived in fraud and executed under cover of a lack of a source of readily available trustworthy information, thus permitting the successful dissemination of gross misinformation and misrepresentation. The pernicious misadvertisement of some lean parts of the state negatives to a considerable degree the work of the various development bureaus composed of citizens who are engaged in legitimate advertising and are annually spending large sums of money for industrial development.

SOIL MAPS. As to the usefulness of trustworthy maps I would call attenion to the general soil maps of the state recently issued by this department. The general opinion of the economic value of these maps is illustrated by the action of the Development Bureau of the Northern Peninsula which had printed for use in advertising the agricultural advantages of that part of the state an edition of 60,000 copies. I might mention also that the Board of State Auditors had printed a special edition of 20,000 copies for the use of the Commissioner of Immigration.

Now good topographical maps are just as essential and valuable, if

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