The radical mound 阝is originally from the character 阜 fù. Characters with the radical mound 阝have to do with “terrain, rise, lower, etc” or its extended meaning.
The radical mound 阝is on the on the left side of a character. It is also called 左耳旁 in Chinese. Actually it has nothing to do with 耳 ear. It is called this way just to simplify the teaching and learning. 阝look like an ear, so it’s called 耳旁。Because the radical mound 阝is on the on the left side of a character, it is called 左耳旁.
Characters with the radical mound 阝
阻、障、隐、防、隔、降、隆、陵、 险、际、附、陆、随、陡、除、陷、隙、陶、限、陌、阪、陋、陛、陕、阱、阿、陈、阳、院、阶、队、阵、陪、陨、隧、隅、陇、阡、隘、etc.