targetgmatchotu wrote:
P1: Two causes
1. Volcanoes
2. Meteorites/Comets = > Iridium
P2: -65 million yrs , iridium was 30 times the normal
C: M/C => Dinosaurs extinction
Now B Says ,Massive volcanic eruptions occurred frequently 80 million years ago.Moreover,nowhere it is mentioned that they were infrequent (-65) million years.
A. Volcanoes massive enough to generate high concentrations of iridium are very rare.
B. Massive volcanic eruptions occurred frequently 80 million years ago.
C. Most scientists support the hypothesis that a cosmic impact wiped out the dinosaurs.
D. The massive extinction that occurred 70 million years ago killed not only the dinosaurs but also 70 percent of all life on Earth.
E. A comet struck the earth some 120 million years ago, but no widespread extinction occurred.
Poorly framed question
Plz Advice !!
The OA is a little debatable but not very much.
(C) is certainly not in the running. Just because other people say it, something doesn't become true. You need facts. Most scientists supporting the hypothesis is not a fact that will help me believe the hypothesis. The reason why most scientists support it, might.
(D) and (E) are irrelevant.
So it comes down to:
A. Volcanoes massive enough to generate high concentrations of iridium are very rare.
B. Massive volcanic eruptions occurred frequently 80 million years ago.
Both support the conclusion to an extent.
In (A), volcanoes massive enough to generate high concentrations of iridium are rare, not impossible. There could have been one 65 million yrs ago. Hence, it doesn't strengthen our belief in a comet/meteor much.
In (B), massive volcanic eruptions occuring frequently through Earth's history while dinosaurs lived doesn't imply that there couldn't have been an especially huge one which wiped out the dinosaurs. But it does make comet/meteor theory more probable.
Look at the argument again - two things cause concentration of iridium - volcanoes and meteors
Volcanoes occured frequently while dinosaurs lived on Earth. Chances are that an activity which was not usual wiped out dinosaurs. Since dinosaurs were wiped out 65 million yrs ago and there was iridium concentration in rocks which are from 65 million yrs ago, it makes it more likely that a meteor wiped out dinosaurs.