CONTENTS.

Page.
Part I. Preparation by Authors.
Introduction[7]
Purpose and value of illustrations[8]
Selection and approval of illustrations[8]
Submittal of illustrations[10]
Kinds of illustrations[10]
Sizes of illustrations[11]
Subdivisions of plates and figures[12]
Preparation of copy by authors[12]
Character of original material[12]
Preliminary preparation of maps[13]
Material available for base maps[14]
Basic features of maps[17]
Standard scales[18]
Orientation of maps[18]
Projection[18]
Explanation[19]
Titles of maps and other illustrations[19]
Symbols used on maps[20]
General features[20]
Letter symbols[20]
Oil and gas symbols[21]
Symbols for use on maps showing features of ground water[21]
Black-line conventions[23]
Materials used in preparing maps[23]
Paper[23]
Bristol board[24]
Tracing linen[24]
Inks[25]
Drawing pens[25]
Pencils[25]
Rubber erasers and cleaners[25]
Colored pencils and crayons[26]
Water colors[26]
Japanese transparent water colors[26]
Coloring geologic maps[27]
Diagrams[28]
Essential features[28]
Plans of mine workings[29]
Sections[29]
Lithologic symbols[32]
Use of photographs as illustrations[32]
Essential features[32]
Copyrighted photographs[33]
Sources of photographs[34]
Lending original photographs and drawings[34]
Unpublished photographs[34]
Specimens[34]
General requirements[34]
Borrowed and fragile specimens[35]
Transmittal of paleontologic specimens[35]
Making up plates[36]
Reuse of illustrations[37]
Approval of finished illustrations[38]
Revision of illustrations[38]
Submittal of proofs[38]
Proof-reading illustrations[39]
General considerations[39]
Part II. Preparation by Draftsmen.
General directions[41]
Instruments[42]
Classification of material[42]
Preparation of maps[43]
Projection[43]
Details of base maps[45]
Transferring or copying[46]
Tracing[46]
Celluloid transferring[47]
Sketching by reticulation[47]
The "shadowless drafting table"[47]
Topographic features[48]
Relief[48]
Hydrography[51]
Cultural features[52]
Lettering[53]
General directions[53]
Lettering by type[54]
Abbreviations[55]
Names of railroads[57]
Make-up of maps[57]
Forms for certain features[57]
Border[57]
Title[58]
Explanation[58]
Graphic scales for maps[59]
Symbols[61]
Areal patterns for black and white maps[61]
Standard colors for geologic maps[63]
Reduction or enlargement of maps[63]
Diagrams[64]
Sections[64]
Plans and cross sections of mines[65]
Drawings of specimens of rocks and fossils[66]
Methods used[66]
Brush and pencil drawings[66]
Pen drawings[67]
Retouching photographs of specimens[68]
Landscape drawings from poor photographs[68]
Pen drawings made over photographs[68]
Brush drawings from poor photographs[69]
Outdoor sketches[69]
Drawings of crystals[70]
Retouching photographs[70]
Part III. Processes of Reproducing Illustrations.
Methods employed[72]
Photoengraving[72]
General features[72]
Zinc etching[73]
Copper etching in relief[75]
Half-tone engraving[75]
Three-color half-tone process[78]
Wax engraving (the cerotype process)[80]
Wood engraving[81]
Photogelatin processes[82]
Lithography[83]
Original process[83]
Photolithography[86]
Offset printing[87]
Chromolithography[87]
Engraving on stone and on copper[89]
Appendix.
Length of degrees of latitude and longitude[91]
Metric system and equivalents[92]
Geologic eras, periods, systems, epochs, and series[92]
Chemical elements and symbols[93]
Greek alphabet[93]
Roman numerals[93]
Mathematical signs[94]
Names of rocks[94]

ILLUSTRATIONS.

Page.
PlateI.Methods of inserting plates and figures[10]
II.Symbols used on geologic maps, economic maps, and mine plans[20]
III.Lithologic symbols used in structure and columnar sections to represent different kinds of rock[32]
IV.Symbols used on base maps[52]
V.Reduction sheet used in lettering illustrations[54]
VI.Half-tone prints showing effects produced by the use of six standard screens[56]
VII.Details of the make-up of a geologic map[58]
VIII.Patterns used to show distinctions between areas on black and white maps[60]
IX.Diagrams and curves[64]
Figure1.Diagrams showing principal, guide, and auxiliary meridians, standard and special parallels and correction lines, and system of numbering townships, ranges, and sections16
2.Conventional lines used in preparing plans and diagrams of mine workings to distinguish different levels29
3.Section and perspective view showing relations of surface features to the different kinds of rocks and the structure of the beds30
4.Sections of coal beds31
5.Diagram illustrating method of projecting a map44
6.Methods of expressing relief by contour lines, by hachures, by shading on stipple board, and by a brush drawing49
7.Designs for bar scales60
8.Method of making a bar scale for a map of unknown scale60
9.Map bearing six areal line patterns62
10.Diagram showing method of marking maps for reduction or enlargement (for record)64
11.Structure section showing method of determining the succession of folds65

THE PREPARATION OF ILLUSTRATIONS FOR REPORTS OF THE United STATES GEOLOGICAL SURVEY.

By John L. Ridgway.

Part I. Preparation By Authors.