The following text is from a 1995 geological survey report describing mineral formations in underground caves.The limestone deposits were so...
GMAT Craft and Structure : (Structure) Questions
The following text is from a 1995 geological survey report describing mineral formations in underground caves.
The limestone deposits were so dense that water could not penetrate them, creating an impermeable barrier that redirected the underground stream toward softer sedimentary layers.
As used in the text, what does the word "dense" most nearly mean?
Compact
Concentrated
Crowded
Thick
Step 1: Decode and Map the Passage
Create Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| "The limestone deposits were so dense that water could not penetrate them," |
|
| "creating an impermeable barrier that redirected the underground stream toward softer sedimentary layers." |
|
Provide Passage Architecture & Core Elements
Visual Structure Map:
[LIMESTONE PROPERTY] Dense limestone deposits → [PHYSICAL CONSEQUENCE] Water cannot penetrate → [GEOLOGICAL RESULT] Stream redirected to softer layers
Main Point: Dense limestone deposits create an impermeable barrier that redirects underground water flow.
Argument Flow: The passage presents a simple cause-and-effect relationship: limestone density prevents water penetration, which forces underground streams to find alternative paths through softer rock layers.
Step 2: Interpret the Question Precisely
What's being asked? This is a Words in Context question asking us to determine the meaning of "dense" as used in this geological context.
What type of answer do we need? The answer must reflect how "dense" functions specifically in this scientific description of limestone deposits and their interaction with water.
Any limiting keywords? N/A
Step 3: Prethink the Answer
- We need to understand what "dense" means when describing limestone that "water could not penetrate."
- In this geological context, we are talking about the physical structure of rock.
- The limestone is described as so "dense" that it creates an "impermeable barrier" - meaning water cannot pass through it at all.
- This suggests the limestone particles are packed very tightly together, leaving no space for water to seep through.
- We are looking for a word that captures this idea of being tightly packed or closely pressed together.
Compact
- "Compact" means closely and firmly packed together.
- This perfectly matches our understanding - limestone that is compact would have particles pressed tightly together with no gaps for water.
- Creates the logical connection: compact limestone → no water penetration → impermeable barrier.
Concentrated
- "Concentrated" means existing in high amounts or intensity in a particular area.
- While limestone deposits could be concentrated in an area, this does not explain why water cannot penetrate them.
- Does not address the physical structure that creates the barrier.
Crowded
- "Crowded" suggests too many things in a space, often with negative connotations.
- This word is typically used for people or objects, not geological formations.
- Trap: Students might think "dense" means "a lot of something" and choose this similar concept.
Thick
- "Thick" refers to the measurement between two surfaces.
- A thick layer of limestone could still be porous and allow water through.
- Thickness alone does not create impermeability - it is about how tightly packed the material is.