context: Warsaw is located on two main geomorphologic formations: the plain moraine plateau and the Vistula Valley with its asymmetrical pattern of different terraces. The Vistula River is the specific axis of Warsaw, which divides the city into two parts, left and right. The left one is situated both on the moraine plateau (10 to 25 m (32.8 to 82.0 ft) above Vistula level) and on the Vistula terraces (max. 6.5 m (21.3 ft) above Vistula level). The significant element of the relief, in this part of Warsaw, is the edge of moraine plateau called Warsaw Escarpment. It is 20 to 25 m (65.6 to 82.0 ft) high in the Old Town and Central district and about 10 m (32.8 ft) in the north and south of Warsaw. It goes through the city and plays an important role as a landmark.
question: What is the axis of Warsaw which divides it into two parts?
answers.text: Vistula River Vistula River Vistula River