The study aims to identify the degree of including the geomorphological concepts in the social studies textbooks grades (5 _ 12) in addition to expose students' acquisition of them in Sultanate of Oman. In order to answer the study's questions, the researcher used a descriptive methodology and prepared a list of geomorphological concepts that supposed to be in the content of these textbooks. The list consists of (96) of geomorphological concepts classified into four domains: geomorphology river valleys; geomorphology wind; geomorphology ice; and geomorphology coasts. Furthermore, the researcher prepared an achievement text comprised of (40) questions. After verifying both the reliability and validity, the 12 social studies textbooks, were analyzed according to the list; and the achievement test were distributed to the sample of students made up of (1000) students from Muscat and Ad Dahirah governorates. The results showed that the degree of including in the social studies textbooks for grades (5-10) repeat reached (727). However, the percentage of was geomorphological concepts varied in the four domains of the social studies textbooks. The geomorphology river valleys was the first on the list with (39.4%). Second, the geomorphology axis wind was with (32.7%). Third, the geomorphology coast was with (26.9%). Finally, the ice geomorphology was with (1.0%). The results also showed a low level of students' acquisition of the geomorphological concepts, where the acquisition percentage was (59.5 %) which is lower than (80%), the acceptable educational level assigned for this study. Additionally, the results showed that there were statistically significant differences in the significance level (a=0.05) can be attributed to the variable of gender in favour of female students and in governorate. The researcher recommend the necessity of including the geomorphological concepts in all domains in social studies textbooks and using different ways to present then in the content. In addition, the researcher highlight the importance of enhancing the students' acquisition of the geomorphological concepts.