The gypsy race flows though the ceremonial centre of rudston [the biggest standing stone in england, a henge, 4 cursus and some of the biggist barrows in england and when visiting you get the feeling that you are now scatching the surface and there was even more there in prehistory].
The water of the river flows above and in places sometimes goes underground and disappears completely [the name gypsy race comes from the fact the river wanders all over just like gypsys do, well some of them anyway!!!], the chalky land of that part of yorkshire has many caverns below ground so if it rains a lot after a period of dry weather [when there is lots of room below ground] the river will disappear, if you reverse this and have lots of rain the caverns will be full, and the river will flow nicely even on the hottest days, so you sometimes get the effect of been dry on wet days and wet on dry days, and i'm sure this would have fascinated the anicents [as it still does], hope that helps, All the best, paul