Arizona silver belt., 1893-01-14
AGE OF THE EARTH.
a FASCINATING STUDY THAT IS ELu-
 COATING A GREAT MYSTERY


 fho president Sir Archibald Gerkie, on
 one of the most interesting problems in
 modern science--the age of the world. Over century has elapsed since James Hutton wrote his Theory of the Earth"
 which was the first attempt to oformulate
 chronology of creation in accordance
 with the discoveries of science; since then knowledge has made vast strides,
 and his followers have access 10 a mass
 of information which be did not possess.
 Playfair and Kelvin improved upon his
 work, and DOW Gerkie and the school to
 which he belongs have gone beyond
 them,
 Gcologists have ascertained that the
 rate at which erosion takes place can be measured; by applying their scale to the
 sedimentary rocks they have formed l hypothesis as to the time which has
 elapsed since erosion began. To put the
 proposition in similar language, lhe sur face of the globe Is constantly wearing
 away under the influence of water and wind The portions which are worn oil | are carried down to the sea or into hol- | lows. where they are deposited and form ! sedimentary rocks. If we can ascertain l how long it takes to form sedimentary rock we can figure out when the progress of wearing away and rcdepositing began.
 Sir Archibald states that on reason able computation the stratited rocks at l tain an average thickness of LOGO feet. The material of which they consist was all washed down from high planes. de- 1 posted and loft to s,ratify By the in- spection of river banks it is found that | in places the surface of the land which has been carried down as sediment in rivers has been reduced at the rate of q foot in 730 years, while in other places, l where the land was more stubborn or less flexible, 1t has taken CISCO years 0 lower the surface one foot The deposit must be equal to the denudation. Tgus We find that while some of the sedimel- i ta1y rocks have grown foot ip 130 1 years others have taken G,500 years to rise that height. Thus me period of 1 tisSye tl0t Nts required to build up QO,- 1 Goo feet of sedimeutary rock has varied according to locality from 73000 GOO years to C&g QOpG90 yeara 1t follows tbnt tue active work of creation lasted for a cycle intermediate between these two figures. The cycle varied with end less succession of periods of disturbance by volcanic force and glacial action. and the frequent suh,aersiou of dry land alfefn=i-g with the emerging of comments ont Of the seas These may have retarded the growth of sedimen- tary rocks, but they cannot hare accel. erated it.
 A study of fossils teaches the steady uniformity with which the work of creation proceeded Since man began to observe there has been no change in i thc forms of animal and vegetable life. A few species have djsaYpeared-no one new species has Seen evolved Not only dowe find the fauna and flora of ancient Egypt as depicted on monuments which | are probably sCg9 or rocco years old ! identical with those which are found ia that country today, but shells which in- hali;ed our seas before the ice age and 1 grew iu au ocean whose bed oyerlay the ! Rocky mountains are precisely the same ! species that are found in the Bay of i Monterey and the waters of the Chesa- peake 1t is eyideht that there has been | no essential change in the conditions Of l life since these animals and these yege- tables were first created, yet how vast l the shortest period which we can assign l 10 Inc gap that divides us from that re- mote epoch!
 Little by little the geologist is lifting ] the veil which covers the prehistoric ! record of our planet The era which | preceded tbe age of civilized man, with | its vast rivers carrying down diluvial | floods to tue ocean, and the bursting forth of mountain ranges from contrac. | tiorsuf the earth'scrust has been tainted i to the life. But no one has exercised lis | pencil on flat preceding age, when tAe | forests made way for clunps of stunled birch and willow, incessant snowfalls coycrcd tue plains glaciers crept down from the Gogth, and gradually a vast sheet Of ice hilf a milo thick drove man kind. with the mamn,5th and tue rein. Beer to thuse fortunate regions which, ike California, escaped the agony of the last ice age.
 Nor have we any distinct perception of that subsequent age when the ice melted or Tsceded to the pole, or dense tropical jungle g'ew up in the Tilorasses it had left, swamps steaming with trop- ical heat swarned with uncouth ba- trachian and reptile life, trees of mon strous growth shed their shade over shiny pools and black ooze, and l the distance long mountain ranges whose fontanel had not yet closed poured a never ceasiug food of lava down their sides. This is q page of history which is yet 10 be written, but the materials are accommodating, and the historian will Dot be long wanting. Francisco Call