Fill in the Blanks Fill in AEOnline version Practice reading and idiomatic expressions by CB Education 1 rock south lake years bowl land moss blue Kerið Crater is a crater in the part of the country Iceland . A crater is an area of shaped like a . Kerið Crater is like a deep , oval - shaped bowl . It has steep sides . The sides are made of reddish . They also have some green moss . This crater formed thousands of ago , when a volcano caved in . Now , the crater has a at the bottom . The lake is shallow and looks . With the blue lake , red rock , and green , Kerið Crater is beautiful to look at !