A Analyze the sea-floor part of the map in Fig. A2.5.1, which depicts the area j

Question

A Analyze the sea-floor part of the map in Fig. A2.5.1, which depicts the area just off the Pacific Coast, west of California, Oregon, Washington, and southwest Canada. The colored hands are marine magmetic anomalies Colored bands are rocks with a positive (+) magnetic anomaly, so they have normal polarity, like now. The white bands are rocks with a negative (-) magnetic anomaly, so they have reversed polarity. Different colors indicate the ages of the rocks in millions of years as shown in the magnetic polarity time scale provided. o 50 IOC mles Moont Meager Mount Cayiey Magnetic polarity time scale: ages are in millions of years ago (Mya) SAN Rainier Mt Mt Hood 2 Mount St Colors incicate rocks of normal magnetic polarity ),ike now The north-seeking end of a compass needie would have pointed in the general direction of the geographic North Pole A y Crest of Juan de Fuca Ridge Three Sisters. Newberry White areas have reversed magnetic polarity (-). At those 8 tmes, the north and south poles eschanged positions The north-seeking end of a compass would have pointed in the general direction of Crater Lake Medicine Lake Volcan volcano Shasta trench -11 the geagraphic South Pole Crest of Ridge 12 west Figure A2.5.1

Explanation / Answer

4 centimeter on scale = 500 km

Distance between point A and C = 3.8 centimeter on figure

Distance between point A and C in kilometer = (3.8/4) x 500

Distance between point A and C in kilometer = 475 km

= 475x 1000 meters = 475,000 meters

475,000 meters = 47,500,000 cm

Time for movement = 8 million years = 8 x 106 years

Therefore, the rate at which points A and C have been moving apart from each other= 47,500,000 cm/8 x 106 years

Therefore, the rate at which points A and C have been moving apart from each other = 5.9375 cm/year

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