If you look carefully at the Geology Map above you can see that some towns are on the red coloured parts (glacial sand and gravel on sandstone) e.g. Howden, Kilpin and Laxton.
These places were chosen by the very early peoples who created homes there. This is because those outcrops were the highest and hardest and least likely to be flooded. Later settlements were created after the water levels had dropped after many hundreds of years of time passing.