ILLUSTRATIONS. 



Page. 



Plate I. Loi;s of the Seaman and lUidil wells and a generali/ed loi;' for iiorth-r(>ntral Texas In pocket. 



Il-V. Spec-ies of Oiilmuhir _ ?:?,~?.l 



VI . .Miiiement chart for graphic eoniputation of thicknes-s of strata 'II 



VII. .Vlinement chart for grajihic com])iitation of depth to a stratum 48 



VIII. Alinement chart for graphic .solution of right triangles 50 



IX. .1. Coconino sandstone and Kaihali limestone in Hurricane fault scar]). G miles south of Hurri- 

 cane, Utah; B. Closer view of middle part of sear]) shown in ^l.- <', U])]X'r ])art of Kailiali 

 limestone and basal member (Rock Canyon) of Moenko]ii formation in Vijgin Canyon, li 



miles west of Virgin ( 'ity, Ttah 58 



X. .1, View northward toward Smith's Mesa from a point just south of Virgin City. Utah: B. 



Panorama along east side of Coal]nts Wash near Grafton. Utah 5!) 



XI. ,1. Chinle formation and overlying massive Jurassic sandstone in Zion Canyon above S]-)ring- 

 dale. Utah; B. Cross-ljedding in white u]i]ier jiart of massive Jurassic sandstone 12 miles 



north of St. George. ITtah ii2 



XII. .1. Grou]) of cinder cones of late date and associated lava. Diamond Valley, 12 miles north 



of St. George. Utah : B. Nearer view of larger cone of grouj) shown in .1 lifi 



XIII. .1. Shinarump conglomerate resting on ujiper Moenko]n shale and sandstone. Smith's Mesa. 

 3 miles north of Virgin City. Utah: B. Late basalt How resting on a conglomerate of basalt 



and other liowlders, on road from Toc(uerville to La Verkin. L'tah 07 



XIV-XXVIll. Koraminifera of the Byram marl 107-122 



XXIX-XXXV. I'oramiuifera of the Mint Spring calcareous marl 146-152 



XXXVI-XL. Fossil plants from the Woodbine sand ISl 



XLl. A. Hills of chloritic schist at the northern end of Big Horn Mountains, near Palo Verde mine, 



Marico])a County, Ariz.; B. lionzales Wells, Dome Rock Mountains, Yuma (.'ounty, .Ariz.. 184 

 XLII. ,1, A ]dug of latite of Tertiary age in the Dome Rock Mountains, al)Out 4 miles southwest of 

 Quartzsite, Yuma < 'ounty, .\riz.: B. Black Butte. Cactus Plain, near Osborne's Well, Yuma 



( "ounty, Ariz 185 



XLIII. A. Osborne Wash, about 2 miles southwest of Osborne's Well, Yuma County, Ariz.; B, Saddle 



Mountain, Maricopa County. Ariz., looking south 188 



XLIV. -1, Bank of wash near Woolsey Tank, Gila Bend Mountains, Maricopa County, Ariz.; B, Woolsey 



Tank. < iila IJend Mountains. Maricojia County. Ariz 189 



XLV. Reconnaissance geologic mapof the lower GUa region, Ariz In ]iocket. 



XLVl. Osage Rock, about 1 mile north of Belvidere, Kans 202 



XLVI I-LX I . Fossil ])lants from the < 'heyenne sandstone 225 



FiGUKE 1. Outline map showing the position of the Seaman and Rudd wells, north-central Texas, and then- 

 relation to the ' ' Bend arch " 6 



2. (reometric representation of the thickness of a stratum when the dip of the stratum and the relative 



[lositions of a ])oint on the upi^er surface of the stratum and another on the lower surface are given . . 40 



3. Diagram to illustrate the method of calilirating the diagonal scale of a 2 chart 43 



4. Diagram to illustrate the method of determining the locus of the curvilinear scale in an alinement 



chart consisting of two ]>arall(4 straight-line scales and a c\irvilinear scali^ 44 



5. Geometric rejiresentation of the distance to a stratum when the dip of the stratum, the position of a 



]ioint on the stratum relative to the starting point of measurement, and the horizontal and vertical 

 directions of the line of measurement are given 47 



6. Right-angled triangle showing the relations of slope distance, horizontal distance, difference of eleva- 



tion, and vertical angle between two station points 48 



7. Diagram illustrating the coml:)ination of three alinement charts for the solution of right-angled 



triangles -19 



8. Diagram illustrating the use of an alinement chart for the solution of the tangent condition in right- 



angled triangles 50 



9. Trigonometric computer for the solution of such problems as are readily solved with the 12-inch 



straigh t slide rule 51 



10. Ma]i showing localities where sections were measured in Washington County, Utah, and Mohave 



County. .\riz 53 



il . Cut in the Woodbine sand near Arthurs I'duff. Tex 180 



IV 



