Obsidian is an igneous rock with a glassy appearance and minimal crystal growth. What accounts for this?
A) Obsidian is an extrusive igneous rock that cooled rapidly on Earth surface, resulting in little crystal growth.
B) Obsidian is an extrusive igneous rock that cooled very slowly on Earth surface, resulting in little crystal growth.
C) Obsidian is an intrusive igneous rock that cooled slowly beneath Earth's surface, resulting in little crystal growth.
D) Obsidian is an intrusive igneous rock that cooled rapidly beneath Earth's surface, resulting in little crystal growth.
A
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From a tunnel in the retreating glacier comes a long, sinuous ridge of stratified gravel laid by the water of an under-ice stream. This feature is called a(n) ________.
Fill in the blank(s) with correct word
Which of the following is the convention used to specify the sequence of bases in DNA?
A) We start at the 3' end. B) We start at the 5' end. C) We start at the end closest to the first adenine. D) we start at the end closest to the first thymine.
You see a foodservice employee trip over a floor mat and fall. She immediately gets up and says she is fine. What should you do?
a. ask her to be more careful b. have an inservice on safety and putting down mats c. ask her to fill out an accident report d. send her home for the remainder of the day even though she said she is fine
Coral reefs
A) require water that is high in sediment concentrations. B) are made of animals living symbiotically with simple algae. C) tend to occur poleward of 30° N/S. D) survive in a broad ecological range because they are tolerant of temperature, salinity, and depth variations. E) are found primarily in deep oceans.