Adapted from "The Greatest Sea-Wave Ever Known" by R. A. Proctor in Wonders of Earth, Sea, and Sky (1902, ed. Edward Singleton Holden)

Far on beyond the shores of New Zealand the great wave coursed, reaching at length the coast of Australia. At dawn of August 14th Moreton Bay was visited by five well-marked waves. At Newcastle, on the Hunter River, the sea rose and fell several times in a remarkable manner, the oscillatory motion commencing at half-past six in the morning. But the most significant evidence of the extent to which the sea-wave traveled in this direction was afforded at Port Fairy, Belfast, South Victoria. Here the oscillation of the water was distinctly perceived at midday on August 14th; and yet, to reach this point, the sea-wave must not only have traveled on a circuitous course nearly equal in length to half the circumference of the earth, but must have passed through Bass's Straits, between Australia and Van Diemen's Land, and so have lost a considerable portion of its force and dimensions. When we remember that had not the effects of the earth-shock on the water been limited by the shores of South America, a wave of disturbance equal in extent to that which traveled westward would have swept toward the east, we see that the force of the shock was sufficient to have disturbed the waters of an ocean covering the whole surface of the earth. For the sea-waves which reached Yokohama in one direction and Port Fairy in another had each traversed a distance nearly equal to half the earth's circumference; so that if the surface of the earth were all sea, waves setting out in opposite directions from the center of disturbance would have met each other at the antipodes of their starting-point.

It is impossible to contemplate the effects which followed the great earthquake—the passage of a sea-wave of enormous volume over fully one third of the earth's surface, and the force with which, on the farthermost limits of its range, the wave rolled in upon shores more than ten thousand miles from its starting-place—without feeling that those geologists are right who deny that the subterranean forces of the earth are diminishing in intensity. It may be difficult, perhaps, to look on the effects which are ascribed to ancient earth-throes without imagining for a while that the power of modern earthquakes is altogether less. But when we consider fairly the share which time had in those ancient processes of change, when we see that while mountain ranges were being upheaved or valleys depressed to their present position, species after species, and type after type appeared on the earth, and lived out the long lives which belong to species and to types, we are recalled to the remembrance of the great work which the earth's subterranean forces are still engaged upon. Even now continents are being slowly depressed or upheaved; even now mountain ranges are being raised to a new level, tablelands are in process of formation, and great valleys are being gradually scooped out. It may need an occasional outburst, such as the earthquake of August, 1868, to remind us that great forces are at work beneath the earth's surface. But, in reality, the signs of change have long been noted. Old shorelines shift their place, old soundings vary; the sea advances in one place and retires in another; on every side Nature's plastic hand is at work modeling and remodeling the earth, in order that it may always be a fit abode for those who are to dwell upon it.

What is the author’s purpose in describing the effects of Bass's Straits on the sea wave?

Adapted from "The Greatest Sea-Wave Ever Known" by R. A. Proctor in Wonders of Earth, Sea, and Sky (1902, ed. Edward Singleton Holden)

Far on beyond the shores of New Zealand the great wave coursed, reaching at length the coast of Australia. At dawn of August 14th Moreton Bay was visited by five well-marked waves. At Newcastle, on the Hunter River, the sea rose and fell several times in a remarkable manner, the oscillatory motion commencing at half-past six in the morning. But the most significant evidence of the extent to which the sea-wave traveled in this direction was afforded at Port Fairy, Belfast, South Victoria. Here the oscillation of the water was distinctly perceived at midday on August 14th; and yet, to reach this point, the sea-wave must not only have traveled on a circuitous course nearly equal in length to half the circumference of the earth, but must have passed through Bass's Straits, between Australia and Van Diemen's Land, and so have lost a considerable portion of its force and dimensions. When we remember that had not the effects of the earth-shock on the water been limited by the shores of South America, a wave of disturbance equal in extent to that which traveled westward would have swept toward the east, we see that the force of the shock was sufficient to have disturbed the waters of an ocean covering the whole surface of the earth. For the sea-waves which reached Yokohama in one direction and Port Fairy in another had each traversed a distance nearly equal to half the earth's circumference; so that if the surface of the earth were all sea, waves setting out in opposite directions from the center of disturbance would have met each other at the antipodes of their starting-point.

It is impossible to contemplate the effects which followed the great earthquake—the passage of a sea-wave of enormous volume over fully one third of the earth's surface, and the force with which, on the farthermost limits of its range, the wave rolled in upon shores more than ten thousand miles from its starting-place—without feeling that those geologists are right who deny that the subterranean forces of the earth are diminishing in intensity. It may be difficult, perhaps, to look on the effects which are ascribed to ancient earth-throes without imagining for a while that the power of modern earthquakes is altogether less. But when we consider fairly the share which time had in those ancient processes of change, when we see that while mountain ranges were being upheaved or valleys depressed to their present position, species after species, and type after type appeared on the earth, and lived out the long lives which belong to species and to types, we are recalled to the remembrance of the great work which the earth's subterranean forces are still engaged upon. Even now continents are being slowly depressed or upheaved; even now mountain ranges are being raised to a new level, tablelands are in process of formation, and great valleys are being gradually scooped out. It may need an occasional outburst, such as the earthquake of August, 1868, to remind us that great forces are at work beneath the earth's surface. But, in reality, the signs of change have long been noted. Old shorelines shift their place, old soundings vary; the sea advances in one place and retires in another; on every side Nature's plastic hand is at work modeling and remodeling the earth, in order that it may always be a fit abode for those who are to dwell upon it.

How does the purpose of the first paragraph primarily relate to the purpose of the second paragraph?