sentences:  The fourth stream originates in Hockley Woods, and is joined by a fifth in Hawkwell, on the edge of the Rochford Basin.Once they enter the basin, they all flow towards its centre, and join up near Rochford.The way in which they are all roughly parallel until they reach the basin, and then change direction, together with the presence of a small chalk inlier near Stambridge Mill, when the chalk layer throughout the area is between below sea level, has led Stratford to suggest that the Rochford Basin may be the result of an impact by an asteroid in the Late Oligocene or Early Miocene periods.