Now, what information needs to go onto a map? Number one, every map needs to have a title which tells us what is on the map. Some examples. This map is simply titled The World. This one, The United States of America.
And this one. California. As soon as you see the title of this map, Geologic Map of California, you know that all those bright colors must represent different kinds of rock, different geology. For detailed study, I'm going to have us look at a map of the Long Beach area.
Here it is. It's awfully small on here, so right after this video I've put a link where you can download the image. of this map and view it, zoom it, pan it on whatever photo viewing app you use on your device.
Looking around the map some major features include the port, the LA river, the traffic circle, the airport, Our LAC campus, our PCC campus, and there's lots lots more. Here's the 405 freeway running across the middle of the map, passing just north of Signal Hill. And you can just see the edge of Naples down in the corner here. shows what happens when government bureaucracy gets mixed up in things. This map seems to have three titles.
Let's zoom in and take a look. There's one on the left, one in the middle, and one on the right. On the left, the US Geological Survey, the organization responsible for these maps. In the center, the state of California not wanting to be left out, and on the right, the real title of the map, Long Beach Quadrangle. A quadrangle is a technical term, means a map whose edges are lines of latitude and lines of longitude.
Next thing, the date. Why do we care about the daytime app? Well, things change over time.
Natural features change pretty slowly, usually, unless we're talking about new land produced by volcanic eruptions, dramatic river changes as a result of a flood and the river choosing a new course. Things like that do happen. But human changes, cultural changes, are happening all the time.
On the Long Beach map, where's the date? Let's zoom in on the map again. This time we're heading towards the bottom and over into the bottom right corner.
There's the date, 1964. Wow, that's over 50 years old. Do you think this map shows everything? about Long Beach the way it is today. Third thing that should be on every map is the legend.
This has nothing to do with ancient myths. The legend shows how we depict different features on the map. What is the significance of black lines, red lines, green lines and so on. If the map's coloured, what the different colors represent.
Here, for example, is the legend on that geologic map of California that I showed you earlier in this video. The different colors are explained as to what kinds of rock they represent. For maps like the Long Beach Quadrangle Sheet that we're looking at, the U.S. Geological Survey publishes maps like this covering the entire country. Rather than reprint the identical legend on every one of those sheets, they publish the legend as a separate page that applies to all the maps.
You have a copy of this legend in your class textbook. If it's too small to read here, don't worry, you will find it as Appendix B at the end of your textbook. I don't expect you to memorize the legend. but you should have a working familiarity with it. For example, how is vegetation represented on the map?
What kinds of vegetation are distinguished? Is there any vegetation shown on the Long Beach map? Where is it? What kind is it? Here in Recreation Park, which is just east of Wilson High School, Along 7th Street there is what is marked as a tract of woodland.
You might say it doesn't look like woodland to me, but there are a bunch of big old eucalyptus trees there, and if you know that area you'll know that every time we have a big winter storm a few more of them blow down. So more than 50 years ago, possibly, it was a more respectable woodland. More legend question. What do rivers and creeks look like?
How can you recognize township and section lines in the public land survey? Actually take another look at this little piece of map by Recreation Park. Running across near the bottom you can see the township boundary line between Tier 4 South and Tier 5 South. And while there are no section boundaries visible, you can see the general location of section 33 and section 34 up above.
All of those questions, and many more like them, can be answered by looking at the legend. Okay, now the fourth key thing on a map is the scale of the map. Vital, date, legend, scale.
The scale is more complex. I need to explain in more detail how that works. A map is a kind of model, reduced simplified version of reality. So let's visualize a model car.
The real car is 16 feet long, the model is 4 feet long. How would you describe the scale of that model? It's a one-quarter scale, isn't it?
16 feet reality, 4 feet model, 4 over 16, 1 over 4, one-quarter scale. We call that a fractional scale. It costs us a fraction.
We also often represent that same information like that. We call that a ratio scale, the colon implying a ratio, but notice there is absolutely no difference between these two. They convey the same information in the same way.
Notice something very important about these scales. There are no units there. Why are there no units?
Because in this ratio there are the same units on both sides. This tells us that one foot on the model represents four feet on the real car, or one inch on the model represents four inches, or one millimeter on the model represents four millimeters in reality. No units because it works perfectly in all units, just so long as you remember to keep the same units on both sides. And I can't emphasize that enough. Same units on both sides.
At some point later on, you guys are going to start telling me that a ratio scale of 1 to 4 means 1 inch represents 4 miles, or something like that. No, 1 inch represents 4 inches, the same units. Now that doesn't reduce things very much. Let's say you wanted to make a plan of your home.
You're about to order a new carpet. They sell it by the square foot. How many square feet in your home? Well, you want to fit your home onto a regular 8.5 by 11 sheet of paper. A scale like 1 to 30 will work real well for that.
Some years ago, quite a few years ago now, the D building in Long Beach City College was completely remodeled. We were all in trailers for a year, and we moved back into the building. And while major concrete structural walls were still in the same place, almost everything else had changed. The individual walls between one room and the next were in different places.
The doors had been knocked through in different ways. places. The floor plan was totally different. Nobody knew how to find where they wanted to go.
So they prepared a floor plan and stuck it up on doors, windows, walls throughout the building so that you could see the way around. It was a slightly bigger thing. It was on an 11 by 17 sheet of paper but the D building is probably a lot bigger than your home. And the scale they used for that was 1, 2, 3, 100. So what does that mean? One inch on the floor plan represents 300 inches.
Oh boy, what the earth does 300 inches look like? Can you visualize that? I don't think any of you can.
Well, let's try dividing that by 12. What do you get? Why am I dividing by 12? Because 12 turns inches into feet, right?
So we could say that that is 1 inch equals 25 feet. I'll use a brief patience on it to write that out. 1 inch equals 25 feet. Is that easier to understand than 1 to 300 or 1 inch equals 300 inches?
It is, isn't it? One inch equals 25 feet. This though has units, it has words in it. So this we call a verbal scale. Verbal because it's in words and now the units are different on the two sides and that only works in those units.
One inch on the map represents 25 feet on the ground or about eight paces. Okay, so this only shrank reality down a little tiny bit, one quarter size. This shrank it down more, one thirtieth.
This shrank it down even more to one three hundredth. Even something like this. We've got a big building onto a sheet of paper.
What if we want to get a city, like Long Beach, onto a sheet of paper? Look at the Long Beach map. What's the scale there? It's 1 to 24,000. One inch on the map represents 24,000 inches.
What would be a good verbal scale for that? One inch. 24,000 inches would be how many feet? Divide by 12. 2000 feet. Okay, you still probably have some trouble visualizing...
you probably still have some trouble visualizing 2000 feet. What would that be in miles? Well there are 5280 feet in a mile.
So we could say one inch is approximately... two-fifths of a mile or approximately one-third of a mile approximately is okay as long as you don't try and say it's exact okay