Map 1-A: The Horn of Africa. Arid regions in green include Ethiopia’s Rift Valley: its Omo Valley and Nech Sar National Park. (Gil, Patricio Robles, Hotspots Revisited)
Map 1-B: The Omo-Turkana Basin (Courtesy International Rivers)
Map 1-C: “Surface Geology and Hydrology of the Lake Turkana Area, Kenya and Ethipia, Africa.” This vertically-exaggerated map also indicates Geologic Periods, was custom-designed for NWNL by Raymond L Straub, PG. View or download high-res. map (554 KB)
Explanatory Note from Map-maker Raymond L Straub: Generally when you are assembling objects for display, especially works that represent potential scientific information, you only include information you can reference or information you personally want to support. Since I have no experience in the Turkana Basin, I have only displayed information I can reference.
The reference material from the USGS used in creating this map gives time periods, but not specific time intervals. Even though those periods are internationally recognized as a specific interval, I did not add specific time since the reference did not include the time interval.
Teritary Igneous is within the Tertiary Period, which represents areas of volcanism or rifting where igneous material was deposited. I do not have any references stating whether the igneous material is intrusive or extrusive. The Tertiary Period has been renamed by the International Commission on Stratigraphy and subdivided into the Paleogene and Neogene periods.
Map 1-D: Details of the Omo-Turkana Basin (Courtesy International Rivers)
Map 1-E: Nech Sar National Park and its Boundaries (Gozalbez & Cebrian. Touching Ethiopia, p. 81)