The present relief of the Žemaitija National Park was formed by the glacier which passed here 10-12 thousand years ago. The whole territory of the park is a part of the Žemaitijos highlands that includes (indicated height above the sea level):
a) Hilly stretch of Plateliai (the highest hill is 188 m heigh),
b) Barstyčiai ridge (the highest hill is 189 m heigh, the average height is 149-154 m),
c) Hilly stretch of Plokštinė (the highest hill is 190 m heigh, 159 m is the dales' height),
d) Plateliai cascade (is formed by the Plateliai group of lakes).
The lowest part in the Park is located 2 km to the southwest from the lake of Ilgis; it is a glade that is 106 m above the sea level. The lowest point is 47 m depression in the lake of Plateliai.
Hilly landscape prevails in the terretory of the Park. The height of the hill slopes is 3,1 m - 19,2 m, with the average of 6,3 m. The slopes are rather flat, with the tilt angle of 1 - 3°; the average steep slope is 7 - 11° and the maximum sharp slope tilt angle is 15°.
Sod-podzolic, bog, sod-bog, sod-podzolic-gley soils are typical for the Park area.
The annual rate of percipitation in the Park is approximately 1000 mm. 56% of percipitation evaporate in the territory of the Park, the rest gets into the rivers through the surface of the land.