第 49 节
作者:嘟嘟      更新:2021-02-20 05:57      字数:9321
  Yesthat is the famous Suspension Bridgeand a beautiful work of art
  it is。  Ay; stare at it; and wonder at it; little man; of course。
  But is it not wonderful?
  Yes:    it was a clever trick to get those chains across the gulf; high up
  in the air:     but not so clever a trick as to make a single stone of which
  those piers are built; or a single flower or leaf in those woods。                The more
  you see of Madam How's masonry and carpentry; the clumsier man's work
  will look to you。       But now we must get ready to give up our tickets; and
  go ashore; and settle ourselves in the train; and then we shall have plenty
  to see   as   we   run   home;   more   curious; to   my  mind;   than   any  suspension
  bridge。
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  And you promised to show me all the different rocks and soils as we
  went home; because it was so dark when we came from Reading。
  Very good。
  * * *
  Now we are settled in the train。        And what do you want to know first?
  More about the new rocks being lower than the old ones; though they
  lie on the top of them。
  Well; look here; at this sketch。
  A boy piling up slates?       What has that to do with it?
  I saw you in Ireland piling slates against a rock just in this way。             And
  I thought to myself〃That is something like Madam How's work。〃
  How?
  Why; see。      The old rock stands for the mountains of the Old World;
  like the Welsh mountains; or the Mendip Hills。               The slates stand for the
  new   rocks;   which   have   been   piled   up   against   these;   one   over   the   other。
  But; you see; each slate is lower than the one before it; and slopes more;
  till the last slate which you are putting on is the lowest of all; though it
  overlies all。
  I see now。     I see now。
  Then   look   at   the   sketch   of   the   rocks   between   this   and   home。 It   is
  only    a  rough    sketch;    of  course:    but    it  will  make    you    understand
  something more about the matter。            Now。      You see; the lump marked A。
  With   twisted   lines   in   it。 That   stands   for   the   Mendip   Hills   to   the   west;
  which are made of old red sandstone; very much the same rock (to speak
  roughly) as the Kerry mountains。
  And why are the lines in it twisted?
  To show that the strata; the layers in it; are twisted; and set up at quite
  different angles from the limestone。
  But how was that done?
  By old earthquakes and changes which happened in old worlds; ages
  on ages since。      Then the edges of the old red sandstone were eaten away
  by the seaand some think by ice too; in some earlier age of ice; and then
  the   limestone   coral   reef   was   laid   down   on   them;   〃unconformably;〃   as
  geologists   sayjust   as   you saw  the  new  red   sandstone  laid   down   on   the
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  edges of the limestone; and so one world is built up on the edge of another
  world; out of its scraps and ruins。
  Then do you see B。         With a notch in it?       That means these limestone
  hills   on   the  shoulder   of   the   Mendips;   and   that   notch   is   the  gorge   of   the
  Avon which we have steamed through。
  And what is that black above it?
  That is the coal; a few miles off; marked C。
  And what is this D; which comes next?
  That     is   what    we     are   on    now。      New      red    sandstone;      lying
  unconformably on the coal。           I showed it you in the bed of the river; as we
  came along in the cab。          We are here in a sort of amphitheatre; or half a
  one;    with   the   limestone     hills  around    us;  and    the  new    red   sandstone
  plastered on; as it were; round the bottom of it inside。
  But what is this high bit with E against it?
  Those are the high hills round Bath; which we shall run through soon。
  They are newer than the soil here; and they are (for an exception) higher
  too;   for they  are   so   much   harder   than   the soil here;   that the sea has   not
  eaten   them   away;   as   it   has   all   the   lowlands   from   Bristol   right   into   the
  Somersetshire flats。
  * * *
  There。     We are off at last; and going to run home to Reading; through
  one   of   the   loveliest   lines   (as   I   think)   of   old   England。 And   between   the
  intervals of eating fruit; we will geologize on the way home; with this little
  bit of paper to show us where we are。
  What pretty rocks!
  Yes。    They are a boss of the coal measures; I believe; shoved up with
  the lias;  the lias   lying   round   them。     But   I  warn   you   I  may  not   be   quite
  right:    because I never looked at a geological map of this part of the line;
  and have learnt what I know; just as I want you to learn simply by looking
  out of the carriage window。
  Look。     Here is lias rock in the side of the cutting; layers of hard blue
  limestone;   and   then   layers   of   blue   mud   between   them;   in   which;   if   you
  could stop to look; you would find fossils in plenty; and along that lias we
  shall run to Bath; and then all the rocks will change。
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  * * *
  Now;   here   we   are   at   Bath;   and   here   are   the   handsome   fruit…women;
  waiting for you to buy。
  And oh; what strawberries and cherries!
  Yes。    All   this   valley   is   very   rich;   and   very   sheltered   too;   and   very
  warm; for the soft south…western air sweeps up it from the Bristol Channel;
  so the slopes are covered with fruit…orchards; as you will see as you get
  out of the station。
  Why; we are above the tops of the houses。
  Yes。    We   have   been   rising   ever   since   we   left   Bristol;   and   you   will
  soon see why。       Now we have laid in as much fruit as is safe for you; and
  away we go。
  Oh; what high hills over the town!           And what beautiful stone houses!
  Even the cottages are built of stone。
  All that stone comes out of those high hills; into which we are going
  now。     It is called Bath…stone freestone; or oolite; and it lies on the top of
  the lias; which we have just left。        Here it is marked F。
  What steep hills; and cliffs too; and with quarries in them!              What can
  have   made   them  so   steep?      And   what   can   have   made   this   little   narrow
  valley?
  Madam How's rain…spade from above; I suppose; and perhaps the sea
  gnawing   at   their   feet   below。   Those   freestone   hills   once   stretched   high
  over our heads; and far away; I suppose; to the westward。 Now they are all
  gnawed out into cliffs;indeed gnawed clean through in the bottom of the
  valley; where the famous hot springs break out in which people bathe。
  Is that why the place is called Bath?
  Of   course。    But   the   Old   Romans   called   the   place   Aquae   Solisthe
  waters of the sun; and curious old Roman remains are found here; which
  we have not time to stop and see。
  Now look out at the pretty clear limestone stream running to meet us
  below; and the great limestone hills closing over us above。 How do  you
  think we shall get out from among them?
  Shall we go over their tops?
  No。    That would be too steep a climb; for even such a great engine as
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  this。
  Then there is a crack which we can get through?
  Look and see。
  Why; we are coming to a regular wall of hill; and …
  And going right through it in the dark。           We are in the Box Tunnel。
  * * *
  There     is  the  light  again:   and    now    I  suppose    you   will   find  your
  tongue。
  How long it seemed before we came out!
  Yes; because you were waiting and watching; with nothing to look at:
  but the tunnel is only a mile and a quarter long after all; I believe。              If you
  had been looking at fields and hedgerows all the while; you would have
  thought no time at all had passed。
  What   curious   sandy   rocks   on   each   side   of   the   cutting;   in   lines   and
  layers。
  Those are the freestone still:        and full of fossils they are。      But do you
  see   that   they   dip   away   from   us?   Remember   that。        All   the   rocks   are
  sloping   eastward;   the   way   we   are   going;   and   each   new   rock   or   soil