Figure 33. Stratigraphic, geophysical-log cross section along southwest margin of San Juan Basin (line of section on Figure 3). Drill-hole depths in hundreds of feet (100 feet approximately 30 m). Cross section shows thinning of Fruitland and Kirtland Formations from northwest to southeast. Coal beds in lowermost Fruitland Formation (near top of Pictured Cliffs Sandstone) are shown. Paleomagnetic data in drill holes 1, 2, 4, and 6 projected from nearby outcrop localities (Figure 3); paleomagnetic data plots on Figure 8, Figure 12, Figure 14, Figure 18, Figure 23, and Figure 28. Palynologic sample-collection levels in drill holes 1, 2, 5, and 6 are projected from nearby outcrop localities; palynomorphs identified from samples listed on Appendix tables, as shown. Top of Fruitland Formation is defined by highest coal bed or carbonaceous shale bed in section (Fassett and Hinds 1971); contact is shown as dashed line because of difficulty locating it with certainty on geophysical logs. Radiometric ages of sanidine crystals from altered volcanic ash beds in Ojo Alamo type area from Fassett and Steiner (1997) and Fassett (2000); stratigraphic levels of dated ash beds are projected into log of drill-hole 2 from measured outcrop localities at or near Hunter Wash (Figure 3). Stratigraphic levels of Puercan mammal sites in lowermost Nacimiento Formation shown in drill-hole logs 2 and 4 from nearby outcrop localities from Williamson (1996) and Lindsay et al. (1981). Vertical exaggeration = 130 x. Distances between drill-hole localities not scaled horizontally.