how can i stop safari from going to the top of page when swiping back?

When i swipe back on safari ( or press the back button ) Safari thinks for a bit and then takes me to the top of the page. this has the effect that i lose my place on the previous page and have to scroll down to find it again. it is very frustrating. I am using the latest version on a new macbook pro. is there a way of turning this off in the preferences?