Page 10 - 4571
P. 10

divided into three major parts: the water portion of our planet, the hydrosphere; Earth’s
                  gaseous  envelope,  the  atmosphere;  and,  of  course,  the  solid  Earth,  or  geosphere.  It
                  needs to be emphasized that our environment is highly integrated and is not dominated
                  by rock, water, or air alone. It is characterized by continuous interactions as air comes in
                  contact with rock, rock with water, and water with air. Moreover, the biosphere, which
                  is the totality of all plant and animal life on our planet, interacts with each of the three
                  physical realms and is an equally integral part of the planet. Thus, Earth consists of four
                  major spheres: the hydrosphere, atmosphere, geosphere, and biosphere.
                         The hydrosphere is a dynamic mass of water that is continually on the move,
                  evaporating  from  the  oceans  to  the  atmosphere,  precipitating  back  to  the  land,  and
                  running  back  to  the  ocean  again.  The  global  ocean  is  certainly  the  most  prominent
                  feature  of  the  hydrosphere,  blanketing  nearly  71%  of  Earth’s  surface  to  an  average
                  depth of about 3800 m. It accounts for about 97 % of Earth’s water. The hydrosphere
                  also  includes  the  freshwater  found  underground  and  in  streams,  lakes,  and  glaciers.
                  Moreover, water is an important component of all living things.
                         Earth  is  surrounded  by  a  life-giving  gaseous  envelope  called  the  atmosphere.
                  This thin blanket of air is an integral part of the planet. It not only the air that we breathe
                  but  also  acts  to  protect  us  from  the  Sun’s  intense  heat  and  dangerous  ultraviolet
                  radiation. The energy exchanges that continually occur between the atmosphere and the
                  surface and between the atmosphere and space produce the effects we call weather and
                  climate.
                         The biosphere includes all life on Earth. Ocean life is concentrated in the sunlit
                  surface waters of the sea. Most life on land is also concentrated near the surface, with
                  tree roots and burrowing animals reaching a few meters underground and flying insects
                  and birds reaching a kilometre or so above Earth. A surprising variety of life forms are
                  also  adapted  to  extreme  environments.  Plants  and  animals  depend  on  the  physical
                  environment  for  the  basics  of  life.  However,  organisms  do  not  just  respond  to  their
                  physical  environment.  Indeed,  the  biosphere  powerfully  influences  the  other  three
                  spheres.  Without  life,  the  makeup  and  nature  of  the  geosphere,  hydrosphere,  and
                  atmosphere would be very different.
                         Beneath  the  atmosphere  and  the  oceans  is  the  solid  Earth, or  geosphere.  The
                  geosphere  extends  from the  surface to the center of the planet, a depth of 6400 km,
                  making it by far the largest of Earth’s four spheres. By examining the most prominent
                  surface features and their global extent, we can obtain clues to the dynamic processes
                  that have shaped our planet.

                         Task  3.  Look  at  Figure  1.2.  Try  to  analyze  what  kind  of  Earth’s  water
                  clearly dominates.  Considering only the nonocean component count the percent of
                  Earth’s fresh water. How much does the groundwater account for?

                         Task 4. Fill in the gaps with one of the suitable words:

                                       a) physical geology, geology, historical geology
                          … means “the study of Earth.” The two broad areas of the science of geology
                  are  …, which examines the materials composing Earth and the processes that operate
                  beneath and upon its surface; and…, which seeks to understand the origin of Earth and
                  its development through time.

                                       b) biosphere, atmosphere,  hydrosphere,  geosphere
                         Soil, the thin veneer of material at Earth’s surface that supports the growth of
                  plants, may be thought of as part of all four spheres. The solid portion is a mixture of
                  weathered rock debris (…) and organic matter from decayed plant and animal life (…).


                                                             9
   5   6   7   8   9   10   11   12   13   14   15