NAU Physics and Astronomy Thesis Defense Johnny Hsu NAU Physics & Astronomy When: Monday, April 22th @ 3:00 PM Where: Physical Sciences, Rm. 321 Investigation of the Relationship of Crater Depths And Diameters in Selected Regions of Mars Impact craters are the common geomorphological features on Mars. The density of craters is different among various regions. The higher crater density means older. Craters can be divided into two types by the interior morphology: simple and complex. The cavity of Simple craters is bowl-shape, and complex craters display various interior features, such as central peaks. The depth/diameter ratio (d/D) of simple craters is larger than that of complex craters. The transition diameter from simple to complex morphologies ranges between 5 and 10 km, and is commonly cited to be about 7 km in the equatorial regions and 6 km near the poles, but the exact value also could vary with terrain type. In this research, 7 regions, Amazonis Planitia, Arabia Terra, Chryse Planitia, Hesperia Planum, Isidis Planitia, Solis/Syria/Sinai Planum, and Terra Sirenum are selected to investigate the onset diameter of complex craters and the relationship of crater diameter and depth in selected regions on Mars in order to understand how the geology affects crater d/D. The analysis revealed that the slopes of the d/D relations are different, and these are linked to the surface material in different regions. The onset diameters in older regions with harder material are slightly higher than younger regions. The research proves that the different geological units can affect the morphology of craters. .