At the top of the blue hole is a layer of ___ water, while below it is a layer of ____ water. The top layer blocks _____ from entering the blue hole.
fresh - salt - oxygen
Match each section of the passage to its purpose: Paragraphs A-B
d - to explain what blue holes are and how they are formed
______ live in between the top and bottom layers.
Bacteria / Brightly colored bacteria
Which part of human or animals from a long time ago can be found in blue holes?
bones
Match each section of the passage to its purpose: Paragraphs E-G
a - to explain the importance of studying blue holes
What helps divers not get lost when swimming in blue holes?
a guideline
Match each section of the passage to its purpose: Paragraph D
b - to show why blue hole exploration is challenging
What is the underneath layer of an inland’s blue hole?
salt water
How deep is Dean’s Blue Hole in the world?
(over) 200 meters
What don’t bacteria living in blue holes need to survive?
oxygen
Match each section of the passage to its purpose: Paragraph C
c- to describe the structure of a blue hole
The gas near the top of the blue hole is _______, and breathing in too much of it can sometimes lead to ______.
poisonous - death