The Geographic Grid #11 video lecture

  • First Exam Content

    • Iso line Map: The first exam will cover topographic maps.
    • Type of Isolines on Topo Maps: Uses contour lines to indicate elevation changes, not isobars (used in weather maps).

  • Understanding Topo Maps

    • Example discussed: La Mesa Quad, a detailed topographic map from US Geological Survey (USGS).
    • Comparison: A simple topo map differs from more complex USGS quad maps like the La Mesa Quad.

  • Reading the Map

    • Key Location: Grosse Mont College is identified on the right side of the sample map.
    • Instructor's Classroom: Located in the northeastern corner of the Grossmont College area on the map.

  • Navigating the Map

    • Starting Point: From the classroom, if walking west along a sidewalk.
    • Driving Directions: Out to the perimeter, intending to head back to Santee.
    • Elevation Note: The elevation for Grossmont College is around 700 feet.

  • Elevation Comparison

    • Other educational locations are at lower elevations:
    • Mesa College and San Diego State at about 500 feet.
    • UC San Diego (UCSD) close to sea level, showcasing Grossmont as a higher education spot in this context.

  • Contour Lines and Elevation

    • 20-foot Contour Interval: Standard interval used in these maps.
    • Index Contours: Every fifth contour line is darkened, simplifying elevation reading; represents 100-foot intervals.

  • Identifying Peaks

    • Peaks can be identified by the contour lines encircling a point, signaling a high elevation (mountain or hill).
    • Cowles Mountain: Example of a local peak; this can be shown through contour encirclement on maps.

  • Ski Routes Example

    • Discusses hypothetical ski routes leading from a chalet at Cowles Mountain:
    • Lift A: Runs parallel to contour lines — not recommended for beginners due to lack of elevation change.
    • Lift C: Goes straight down through contour lines — the steepest but challenging.
    • Lift B: Recommended for beginners — crosses lines at a mild angle for a gentler slope.

  • Hiking Route Example

    • Activity visualization: Assessing quickest and safest routes navigating slopes.
    • Assumption: A senior citizen with mobility difficulties needing to travel from point one to two (bathroom) should avoid steep climbs.
    • The optimal path would be parallel to contours, avoiding elevation changes that could lead to immobility or injury.

  • Elevation Journey

    • Describes walking from Cowles Mountain down to varying elevations:
    • Progressing from 700 feet up to 1,591 feet at the summit of Cowles Mountain, before heading back down with dips in elevation along the way.
    • Encountering other small peaks along the journey illustrates the dynamic nature of the local geography.

  • Conclusion: Understanding elevation through reading contour lines is crucial. Contour maps reveal terrain features and elevation changes; learning to interpret these is essential for navigation and geographic comprehension.