Graphics Interpretation: Earth's geological history

[nyc917]

Source: http://www.mba.com/the-gmat/nex-gen/samples/Sample-471

The diagram shows, in three column groupings, various divisions of Earth's geological history since its formation approximately 4,600 million years ago. In the leftmost column grouping, the Precambrian eon is subdivided into chronometric eons shown on the far left; but otherwise, in the rest of the graphic, each subsequent column to the right shows the subdivisions of the timeframes to its left. Each of the rightmost two column groupings is a magnification-with additional information-of a portion of the grouping directly to its left.

According to the diagram the beginning of the Cambrian period / Triassic period / Pliocene epoch / Precambrian eon marks the onset of a new eon, era, and period in geological history.

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Stacey has already put together a great analysis on how to approach this problem: http://www.manhattangmat.com/blog/index.php/2012/03/28/the-next-gen-gmat-graphics-interpretation-2/

However, I have a question on the second part of this question.

The question asked, according to the diagram the beginning of the xxxx marks...

Looking at the correct answer, Cambrian, the beginning of this period is not exactly the onset of a new eon, era, and period in geological history. It should be the "end", right? Or am I not reading this correctly?

[tim]

Tricky one, but you have to read the diagram from the bottom up! :) The beginning of the Cambrian is at the bottom, because the bottom of the diagram is the oldest time period.

[nyc917]

Tricky one, but you have to read the diagram from the bottom up! :) The beginning of the Cambrian is at the bottom, because the bottom of the diagram is the oldest time period.

Got it, thanks Tim.

[tim]

Any time!