Суммируйте приведенную ниже информацию в одном предложении и дайте на ее основе определения известнякам и песчаникам

1.

· Limestone is a rock.

· It consists essentially of calcium carbonate.

· It is partly of organic origin.

· It contains the hard parts of various organisms.

Thus, limestone is a type of rock which ………..

2.

· Sandstones are rocks.

· They are sedimentary rocks.

· They are composed of grains of sand.

· They exhibit a variety of colours.

Thus, ……………… are referred to as sandstones.

Ex.12.