1.The whole interior of Greenland is covered with an immense ice-cap，many hundred feet in thickness.Even in summer the heat of the sun is powerless to melt this mass，which only freezes into greater solidity when that heat is withdrawn.The immense pressure of the new snowfall of each year helps to turn the lower parts into solid ice.
2.The great weight of snow also acts as a propellingpower，and forces the icy stream down the valleys towards the coast，where it appears as an enormouscrystal precipice.At last the front of the glacierisforced into the sea，and into deeper and still deeper water.It begins to feel the action of the waves and tides，which wear away its base，and great cliffs of ice overhang the ocean.
3.A lofty cliff of ice，thus overhanging the water，begins to show signs of insecurity.Great caverns havebeen formed in its base，deep fissuresare discerniblein its surface.Suddenly，with a roar far louder than thunder，the ice-mountain snaps asunder，and the detached mass comes crashing down.A cloud of spray dashes high into the air，and a young iceberg is born.It dives as it touches the waves，rises slowly，sways and tumbles to and fro，but at last finds its balance.Its front is one hundred and fifty feet above the waves；but there is about nine times as much bulk beneath as above the surface.
4.The berg is scarcely launched into life before it begins to feel the influence of the great Arctic Current that flows southward through Baffin Bay and DavisStrait.Borne on the bosom of this stream，it starts on its long voyage of six or possibly twelve months.As the berg reaches a warmer climate，the silent rays of the sun and the action of the warmer air begin slowly to take effect：streamlets trickle down its sides；great crags ever and anon fall from it with a sullen plunge into the ocean.
5.Soon it becomes top-heavy-it reels and turns over.Rocky fragments embedded in its now upturned base are exposed to the light.The berg presents a completely new front，and is no longer recognizable as the same towering monster that left the portals of the North months before.It is in a state of unstableequilibrium，and as fragments are broken off，itfrequently turns over with a hoarse roar.All sailors know how dangerous are icebergs in this condition.They call them “growlers，”and give them a wide berth.
6.Greatly reduced in size，the berg still holds on its course，and approaches the banks of Newfoundland.Now it enters the warm water of the Gulf Stream，andits dissolutionis at hand.Cascadesare streamingdown its sides；caverns are worn right through its centre；small lakes are formed on its summit；rents andfissures are constantly widening；finally，it fails to pieces with a noise like thunder.Its shattered remains are scattered far and wide，and speedily melt in the warm waters.The berg is no more.
7.Such is the life-history of an iceberg.When it reaches a certain stage-when it becomes “rotten，”as the sailors say-it is especially dangerous.Then a slight cause will make it break up into fragments，raising hugebillows which might swamp a vessel.The concussionofthe air from the firing of a gun，or even the noise made by a steamer，has been known to cause the breaking up of an iceberg.
8.Sometimes a berg has projections or spurs underneath the water，stretching far out from its base，and a vessel that ventures too near may strike on one of these unseenice-reefs.In July 1890，a steamer with touristsonboard，who were anxious to have a near view of a large berg，approached so close that she struck on one of its projecting spurs.The shock and the weight of the vessel broke off the spur，and at the same time a huge piece of the berg，many hundreds of tons in weight，fell into the water with a fearful roar close behind the steamer.A great wave lifted her stern，and she seemed to be going to the bottom；but the good ship came slowly up，her deck covered with ice fragments，and cataracts of water streaming from her sides.It was an extremely narrow escape.
9.There are many berg-producing glaciers on the Greenland coast.The largest known，the Humboldt，was reported by Dr.Kane as extending forty miles along the coast，and presenting a perpendicular front three hundred feet high.This glacier is nine hundred feet thick，and advances at a rate of forty-seven feet a day.
10.Sir John Ross once saw an iceberg two and one-fifth miles broad，two and one-half miles long，and one hundred and fifty-three feet high.In the southern hemisphere much larger bergs have been seen，towering from seven hundred to eight hundred feet above the waves.It must not be forgotten that in estimating the size of an iceberg，the visible portion is only one-tenth part of the whole mass.