The Neris Regional Park preserves the most valuable section of the Neris Valley, its most picturesque landscape. The Zabarija Hills that open up before your eyes are one of the most impressive landscape elements in the entire regional park. They remind us of the mighty Neris River that once flowed here, which was several kilometers wide in this place. Now we are standing at the bottom of the former mighty river, and the undulating hills visible in the distance are the banks of that old glacial meltwater river. Below Vilnius, within the boundaries of the Neris Regional Park, the Neris crosses the Baltic Uplands pushed by the last glacier, dividing them into two parts, separating the Trakai and Sudervė hills. The river had to work hard here until its bed was widened and deepened. This is evidenced by the valley slopes rising up to 70–80 m high on both sides of the bed. The wide, 3–5 km wide, old Neris Valley extends for more than 40 km. Much more powerful water flows flowed from the wide pre-glacial lagoons than the current river. Thus, in the place of the current Neris, a much wider and more watery river of ice meltwater once flowed, forming a wide ancient valley. While the glacier had blocked its path towards the Baltic Sea, it flowed in the opposite direction than it does now – it carried its waters to the southeast! Moreover, the predecessor of the Neris was not as winding as the current one. It eroded the upper (IV–VII) terraces of the Neris valley – this is evidenced by the ravines formed by the melting of buried ice. As the glaciers and pre-glacial lagoons retreated, soil gradually formed on the dead terraces and slopes. A lot of time passed before the valleys of the Neris and its tributaries became green with forests. Different formations of the earth's surface deposits determined the diversity of stands. The coniferous massifs that dominate the valley are diversified by deciduous trees, which turn various shades of green in spring and yellow, brown and red in autumn. Then the valley landscape comes to life. Due to the different humidity (the terraces, especially the floodplain, are in places waterlogged due to excess moisture), the diversity of low plants in soil types is even greater than in stands.