On the map on the previous page, highlight the mid-ocean ridge in the Elrond Sea and label it the Hobbit Ridge. 2. The pattern of positive and negative magnetic anomalies in the Elrond Sea can be correlated with the pattern of normal and reversed magnetism on the magnetic polarity time scale. Based on this correlation, how many millions years (m. y.) ago did sea floor spreading begin in the Elrond Sea? m. y. ago 3. Using the magnetic anomaly pattern in the Elrond sea, determine the 1/2-spreading rate on the Hobbit Ridge (i. e., determine how fast the Frodo continent is moving away from the Hobbit ridge). Give your answer in mm/y (millimeters per year). Show your equations. Useful Information: 1 cm (10 mm) on the map = 400 km on Geoworld 1 mm/y = 1 km/m. y. (kilometers per million years) distance = rate x time, rate = distancetime , time = distancerate