About 70 percent of the Korean Peninsula is mountainous or hilly. The mean elevation of Korea is 433 m and the mean slope angle is 10.4˚. The northeastern part is the most rugged area where mountain ranges such as Baekdusan (Baekdu Mountain) rise to over 2,700 m in places. The Taebaeksanmaek (Taebaek Mountain Range) rises to over 1,500 m on the eastern side of the peninsula and then drops abruptly toward the East Sea with little or no coastal plain. Narrow valleys and plains are located between the hills and mountains in this area. In the central zone, moderately high mountains dominate the landscape. The west and south coasts in the southern half of the country are deeply indented with many islands and harbors. Lowlands are found mainly along the western sides of the peninsula, with some extensive lowlands also in the south. Elevations are generally low, because these mountain ranges have been subjected to long-term erosion with relatively stable tectonic movements. In the low relief region of southwestern Korea, there are abundant 'monadnock' features thought to have been formed by long-term surface erosion.

A profile of central Korea reveals that the eastern side of the Taebaeksanmaek has high relief, while the western flank has widely spaced hills with low relief. These landforms of the entire area are believed to have been formed by asymmetrical tectonic movement centered along the Taebaeksanmaek. This uplift seems to have begun during the middle of the Cenozoic era after a long period of planation during the Mesozoic era.

The distribution of mountain ranges dominates the overall pattern of landforms in Korea. Mountain ranges in Korea are divided into two categories based on their genesis. Primary mountain ranges are closely related to tectonic movement and include Taebaeksanmaek, Nangnimsanmaek, Hamgyeongsanmaek, and Sobaeksanmaek. These ranges have been formed by asymmetrical uplift and faulting during the Cenozoic era and are continuous with no breaks in the mountain ranges. On the other hand, secondary mountain ranges formed by differential erosion processes are lower and individual peaks are separated by lower altitudes.

A number of high altitude (800-1,000 m) plateaus, a typical landform of northern Korea, are found in the Gaemagowon (Gaema Plateau) and Taebaeksanmaek including Baekdugowon, Gaemagowon, Nangnimgowon, Bujeongowon, and Jangjingowon. A low-relief surface is thought to have existed before uplift. The remnants of this flat surface are still observed at higher elevations among the Taebaeksanmaek, and are often referred to as a 'high flat surface (paleo-erosion surface).' Along the upper tributaries of main rivers, there are some basins which have been formed by the erosion on the 'high flat surface.' In these cases, the bedrock is mainly granite surrounded by metamorphic and other lithologies. At lower altitudes along the rivers, there are 'low flat surfaces (neo-erosion surface),' which evolved from the 'high flat surface.' These 'low flat surfaces' exhibit flat and low relief landforms.