Question

Earth Science Elevations are measured from sea level, which is considered to have an elevation of 0 feet. Elevations above sea level are positive, and elevations below sea level are negative. In Exercises \(9-13,\) use this table, which shows the elevation of the lowest point on each continent. $$\begin{array}{|l|c|r|} \hline \text { Continent } & \text { Location of Lowest Point } & \text { Elevation } \\ \hline \text { North America } & \text { Death Valley } & -282 \mathrm{ft} \\ \text { South America } & \text { Valdes Peninsula } & -131 \mathrm{ft} \\ \text { Europe } & \text { Caspian Sea } & -92 \mathrm{ft} \\ \text { Asia } & \text { Dead Sea } & -1,312 \mathrm{ft} \\ \text { Africa } & \text { Lake Assal } & -512 \mathrm{ft} \\ \text { Australia } & \text { Lake Eyre } & -52 \mathrm{ft} \\ \text { Antarctica } & \text { Bentley Subglacial Trench } & -8,327 \mathrm{ft} \\ \hline \end{array}$$ How much lower is the Dead Sea than the Caspian Sea?

Short answer

The Dead Sea is 1,220 ft lower than the Caspian Sea.

Step-by-step solution

Identify the Elevations

Find the elevations of the Dead Sea and the Caspian Sea from the table. The elevation of the Dead Sea is \(-1,312 \text{ ft}\) and the elevation of the Caspian Sea is \(-92 \text{ ft}\).

Subtract the Elevations

To find how much lower the Dead Sea is compared to the Caspian Sea, subtract the elevation of the Caspian Sea from the elevation of the Dead Sea: \[-1,312 \text{ ft} - (-92 \text{ ft})\]

Simplify the Subtraction

Simplify the expression by removing the parentheses: \[-1,312 \text{ ft} + 92 \text{ ft}\]

Calculate the Difference

Perform the addition to find the difference in elevation: \[-1,312 + 92 = -1,220 \text{ ft}\]

Key concepts

Elevation Differences

Elevation describes the height or depth of a point relative to sea level. Earth scientists measure elevations to understand landforms, the Earth's structure, and various ecological factors.
When discussing elevations:

• Positive values indicate heights above sea level.
• Negative values signify depths below sea level.

For instance, the table provided in the exercise lists the lowest points on each continent, with places like Death Valley and the Dead Sea having negative elevations because they lie below sea level. This negative value helps in determining how deep they are compared to the reference sea level, which is set at 0 feet.

Subtraction of Integers

When subtracting integers, especially involving negative numbers, it’s important to pay attention to the signs.
The exercise requires us to find the difference in elevation between the Dead Sea and the Caspian Sea. Here’s how you do it:
\begin{itemize}

Identify the values: The Dead Sea at \( -1,312 \text{ ft} \) and the Caspian Sea at \( -92 \text{ ft} \).

Set up the subtraction problem: \( -1,312 \text{ ft} - (-92 \text{ ft}) \).

Change subtraction of a negative to addition: \( -1,312 \text{ ft} + 92 \text{ ft} \).

Now, perform the addition to get the final result of \-1,220 \text{ ft}\. So, the Dead Sea is 1,220 ft lower than the Caspian Sea.

Earth Science Importance

Understanding Earth’s elevations plays a significant role in various disciplines:

• Geology: Helps in studying Earth's physical structure and substance.
• Hydrology: Critical for water resource management and understanding drainage basins.
• Ecology: Influences climate, habitat distribution, and biodiversity.

Accurately measuring and comparing elevations gives scientists insights into tectonic activity, erosion processes, and potential natural disasters. The data in the exercise, such as the depths of various low-lying points, can also inform policy-making and land-use planning.

Negative Numbers

Negative numbers often represent points or quantities less than zero. In Earth science, they’re particularly useful in indicating elevations below sea level.
Here’s a quick rundown:

• Negative Signs: Indicates a depth below a reference point, such as sea level.
• Calculations: When subtracting negative numbers, remember \( a - (-b) = a + b \).

Applying these concepts to the exercise, comparing elevations (like the Dead Sea and Caspian Sea), becomes straightforward. Instead of viewing negative elevations as confusing, understand that they simply indicate depths beneath the generally accepted sea level.