1014 -Subsurface Geologic Methods 



index wall map adjacent to the filing cases facilitates locating of file data. 

 Ordinate lines and values of the 100,000' grid system are posted in India 

 ink on a U.S.G.S. geological wall map of the United States (Scale: 

 1/2,500,000) or of North America (Scale: 1/5,000,000). The previously 

 omitted first portion of the provincial ordinate values is entered adjacent 

 to, yet separated from, local ordinate index values to facilitate regional 

 filing (figs. 543b, c, d). 



East ordinate regional filing is in progression of 100,000' square 

 east-boundary ordinate-index values. Index-tabbed Manila sheets (91" 

 X 11^'") separate note and data sheets at 100,000' easting intervals. The 

 regional index value indicated on the note sheet will be a two- or three- 

 digit number (the last five digits are reserved for local use) . A Manila 

 index sheet is inserted to indicate a last-digit change of the regional index 

 value: thus, 335, 336, 337, etc. The easting-index value is entered on the 

 tab. To insure filing-tab visibility, positions of the index tabs are offset 

 or staggered systematically on each successive Manila divider sheet as 

 indicated in figure 535a. 



The illustrated arrangement makes possible decimal filing. There are 

 ten index tabs in each row; each tab is successively offset to the left 1.1". 

 North-ordinate regional filing is subsidiary to east-ordinate filing. 

 Manila divider sheets with indicated north-index values further separate 

 the data within each 100,000' easting interval on the basis of 100,000' 

 northing-ordinate intervals. On the index tabs, north-ordinate values are 

 entered underneath the east-ordinate values. Ordinate values are typed 

 on 2" Dennison gummed labels and mounted on the tab as shown in 

 figure 535b. 



An index map showing coordinate control, major physiographic and 

 cultural features and political subdivisions is mounted on each index tab 

 sheet. Standard 10,000' scale office-map prints (20"x 40") are subdivided 

 to 100,000' square areas, cut, and mounted on the index divider sheets; 

 or U.S.G.S. topographic sheets may be cut and "edited" to the proper 

 100,000' square areas and mounted on the index sheets. On these maps 

 the local unit-note-sheet areas that have been mapped are indicated by 

 color. Various colors are utilized to indicate the mapping scale: 



1"= 10,000': White 



1"= 5,000': Buff 



1"= 1,000': Orange 



1"= 200': Green 



1"= 50': Blue 

 Local filing is based on local areal subdivisions described under 

 "Note Sheet Grid System." The areal grid is derived from 8"x 10" note- 

 sheet map areas, when the following scales are utilized: 1" = 50', 1" = 200', 

 1" = 1,000', 1" = 5,000'. Data mapped to any of the above scales is 

 placed in the same file drawer. All planar and sectional data representing 

 any one unit rectangle are placed in a Q^'x 11^" Manila file folder. The 



