At the end of the Triassic period 200 million years ago, there was a mass-extinction event that caused the extinction of more than half of all living species. It was this extinction event that allowed dinosaurs to become the dominant species for the next 145 million years. We do not know exactly what happened that eliminated so many species in a relatively short period of time, but there are several possible explanations.
One theory involves the decline of sea levels. Near the end of the Triassic period, sea levels were fluctuating. When sea levels fall, the habitats for ocean populations that live in the shallows and land species that live on the coast are destroyed. The destruction of coastal and shallow-ocean species would have had a profound effect on food chains worldwide, leading to mass extinctions.
Another theory involves massive climate cooling. The end of the Triassic period was marked by widespread volcanic activity. The volcanoes released large amounts of sulfur dioxide (SO2). A rise in atmospheric SO2 is known to cause a lowering in global temperatures. Such climate change could have devastated many species and led to the extinctions.
The third theory involves an asteroid strike. Asteroids (objects from outer space) occasionally collide with Earth. When an asteroid hits Earth’s surface, it often displaces large amounts of soil and crushed rock, leaving behind a depression, or crater. The displaced debris is thrown up into the atmosphere where it can block out sunlight for many months or even a few years. A sufficiently massive asteroid impact at the end of the Triassic period may have blocked sunlight long enough for most plants to die and many animal species to then starve.
The reading passage provides three possible explanations for the mass extinction at the end of the Triassic period 200 million years ago. However, the lecturer thinks the three explanations from the reading are not convincing. She casts doubt on the mains reasons by giving three arguments.
First of all, according to the reading passage, the decline of sea level as a reason for the mass extinctions. But the lecturer refutes this idea. She believes that the sea level has indeed changed near the end of the Triassic period. Sea levels were fluctuating. But this situation has been usual for the species to adjust the surroundings. What’s more, the fall of the sea levels was gradual, and it took a long time to destroy the ocean populations and land species. Therefore, the decline of sea levels would not lead to mass extinctions.
Secondly, the reading passage states that massive climate cooling resulted in mass extinctions. Nevertheless, the lecturer refutes the point. She thinks that eruption of volcanic activity has not last very long time. Sulfur dioxide which released by the volcanic activity presented in the air. After several years, the acid has been cleaned out. And there is no more sulfur dioxide. Furthermore, water came back. Thus, the cooling global temperature is impossible to explain the extinctions.
Finally, the author of the reading passage reckons that an asteroid is responsible for mass extinctions. On the other hand, the lecturer does not agree with the opinion. She maintains that there is a few of experts believe that an asteroid strike led to mass extinctions. Because some experts has dated the crater which left by the collision between asteroid and earth, the result shows that the time of the crater is much earlier than mass extinctions.
| Post date | Users | Rates | Link to Content |
|---|---|---|---|
| 2020-01-17 | nusybah | 80 | view |
| 2019-11-14 | M.S 2019 | 76 | view |
| 2019-10-24 | p0uya | 65 | view |
| 2019-10-24 | Seema Modak | 71 | view |
| 2019-10-08 | mahan vahab kashi | 80 | view |
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Grammar and spelling errors:
Line 3, column 549, Rule ID: WHITESPACE_RULE
Message: Possible typo: you repeated a whitespace
Suggestion:
...els would not lead to mass extinctions. Secondly, the reading passage states tha...
^^^^
Transition Words or Phrases used:
but, finally, first, furthermore, however, nevertheless, second, secondly, so, therefore, thus, first of all, on the other hand
Attributes: Values AverageValues Percentages(Values/AverageValues)% => Comments
Performance on Part of Speech:
To be verbs : 10.0 10.4613686534 96% => OK
Auxiliary verbs: 1.0 5.04856512141 20% => OK
Conjunction : 6.0 7.30242825607 82% => OK
Relative clauses : 9.0 12.0772626932 75% => More relative clauses wanted.
Pronoun: 14.0 22.412803532 62% => OK
Preposition: 30.0 30.3222958057 99% => OK
Nominalization: 3.0 5.01324503311 60% => More nominalizations (nouns with a suffix like: tion ment ence ance) wanted.
Performance on vocabulary words:
No of characters: 1504.0 1373.03311258 110% => OK
No of words: 293.0 270.72406181 108% => OK
Chars per words: 5.13310580205 5.08290768461 101% => OK
Fourth root words length: 4.13729897018 4.04702891845 102% => OK
Word Length SD: 2.69148064697 2.5805825403 104% => OK
Unique words: 157.0 145.348785872 108% => OK
Unique words percentage: 0.535836177474 0.540411800872 99% => OK
syllable_count: 444.6 419.366225166 106% => OK
avg_syllables_per_word: 1.5 1.55342163355 97% => OK
A sentence (or a clause, phrase) starts by:
Pronoun: 4.0 3.25607064018 123% => OK
Article: 12.0 8.23620309051 146% => OK
Subordination: 2.0 1.25165562914 160% => OK
Conjunction: 4.0 1.51434878587 264% => Less conjunction wanted as sentence beginning.
Preposition: 3.0 2.5761589404 116% => OK
Performance on sentences:
How many sentences: 22.0 13.0662251656 168% => OK
Sentence length: 13.0 21.2450331126 61% => The Avg. Sentence Length is relatively short.
Sentence length SD: 37.1817348299 49.2860985944 75% => OK
Chars per sentence: 68.3636363636 110.228320801 62% => OK
Words per sentence: 13.3181818182 21.698381199 61% => OK
Discourse Markers: 5.77272727273 7.06452816374 82% => OK
Paragraphs: 4.0 4.09492273731 98% => OK
Language errors: 1.0 4.19205298013 24% => OK
Sentences with positive sentiment : 2.0 4.33554083885 46% => More positive sentences wanted.
Sentences with negative sentiment : 6.0 4.45695364238 135% => OK
Sentences with neutral sentiment: 14.0 4.27373068433 328% => Less facts, knowledge or examples wanted.
What are sentences with positive/Negative/neutral sentiment?
Coherence and Cohesion:
Essay topic to essay body coherence: 0.172029676662 0.272083759551 63% => OK
Sentence topic coherence: 0.0423633098161 0.0996497079465 43% => OK
Sentence topic coherence SD: 0.0729887548348 0.0662205650399 110% => OK
Paragraph topic coherence: 0.0972406594071 0.162205337803 60% => OK
Paragraph topic coherence SD: 0.0671114391175 0.0443174109184 151% => OK
Essay readability:
automated_readability_index: 9.4 13.3589403974 70% => Automated_readability_index is low.
flesch_reading_ease: 66.74 53.8541721854 124% => OK
smog_index: 3.1 5.55761589404 56% => Smog_index is low.
flesch_kincaid_grade: 7.2 11.0289183223 65% => OK
coleman_liau_index: 11.59 12.2367328918 95% => OK
dale_chall_readability_score: 7.95 8.42419426049 94% => OK
difficult_words: 68.0 63.6247240618 107% => OK
linsear_write_formula: 5.5 10.7273730684 51% => Linsear_write_formula is low.
gunning_fog: 7.2 10.498013245 69% => OK
text_standard: 8.0 11.2008830022 71% => OK
What are above readability scores?
---------------------
Rates: 71.6666666667 out of 100
Scores by essay e-grader: 21.5 Out of 30
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Note: the e-grader does NOT examine the meaning of words and ideas. VIP users will receive further evaluations by advanced module of e-grader and human graders.