context: To the north of Gdynia there is a small plateau that rises 60-80 m above the surrounding area. This plateau, or the so-called Oxhefst bridgehead, is surrounded by the sea from the east and partly from the south, and by the marshy lowlands from the north, west and southwest. Strong fortifications were created on this plateau by the enemy, which, in combination with the natural conditions of the area , covered the approaches to Gdynia from the north. Terrain conditions (rugged terrain, swamps, forest and sea) strengthened the German defense and, conversely, extremely impeded the advance of the Soviet troops. With a relative lack of roads, it was impossible to use tanks and self-propelled artillery installations with full effectiveness.
question: What was the basis of the Pomeranian fortifications?
answers.text: , covered the approaches to Gdynia from the north