Chattahoochee Bend Mapping Project

All the big geological features in this section of the map run southwest to northeast, so it’s no surprise that the big creek runs – southwest to northeast. I don’t know where this creek begins, because it does not cross any of the roads south of the map. It’s pretty big for having such a short run. It crosses the road on the northeast corner of the map on it’s way to the river. How big is it?

From Chattahoochee Bend

Not as big as the creeks at Cochran Mill. More the size of the creek at Pickett’s Mill. There won’t be any problem crossing it during normal water levels – although you will get your feet wet. Here’s where one of the old roads fords the creek:

From Chattahoochee Bend

My plan is to finish everything north of the creek before crossing it and mapping the other side. At one spot there is a very nice beaver swamp and impressive dam:

From Chattahoochee Bend

That’s the dam in that photo bending across. I thought maybe I would get a break from the boulders down in this section, but it’s not to be. There are some huge rock gardens that are awaiting mapping:

From Chattahoochee Bend

From Chattahoochee Bend

Here’s another map sample, this one with a variety of bare rock and boulder features to ponder, including a couple of boulders drawn to scale (the black blobs). Click to see the whole thing:

From Chattahoochee Bend

From Chattahoochee Bend

Boulder count is about 300. Ocad (the map CAD software) has a feature where it will count all instances of a symbol. 300 seems like a lot, but it’s not really. The Red Top State Park map, by comparison, has around 1500 boulders. Of course, I am still not halfway done with this map, so the number of boulders will certainly climb. What is unique about Chattahoochee Bend is that the boulders are not evenly distributed (like they are at Red Top). They are in bands, running across the map. And they are much larger than the boulders at Red Top. The largest I have found so far is 16 meters by 20 meters and 5 meters tall. That’s big enough to be mapped “real size”. Instead of using a black dot or triangle, the boulder is drawn in black to scale on the map – impressive.

From Chattahoochee Bend

From Chattahoochee Bend

From Chattahoochee Bend

From Chattahoochee Bend

From Chattahoochee Bend

It is also very challenging to map so many boulders. I spent five hours on Saturday doing an area only about 300 meters square. Deciding what not to map is very important, as is deciding which symbol to use – small dot, large dot, triangle, irregular triangle, or mapped to scale. Here’s a small example:

From Chattahoochee Bend

Big snow yesterday, Saturday 2/13/2010. Probably about 3 inches on the map. So I waited for it to drip off the trees and melt away before heading out there today. Forecast for overnight is even more snow.

From Chattahoochee Bend

I am almost done with another page of the basemap. Worked my way down, down, down and discovered a little pond in the bottom corner of this page.

From Chattahoochee Bend

I cannot figure out the pattern of the boulders. It’s either feast of famine. There were dozens on the west side of the spur I am working on, and two on the east side. They are in bands. Once the map is drafted that will probably be obvious, but it’s certainly puzzling to the poor mapper while he is out there trying to plan the best use of his time!

And the next spur to the east is covered with more bare rock areas. It looks as if the big shallow reentrant repeats again three or four hundred meters east. But that will all be revealed over the next few trips.

Now that I am mapping boulder fields I thought I would describe the process of how I measure the distance between boulders and place them on the field notes. This process works for anything that needs to be measured.

I use a metal ruler, six inches long, with one edge metric and the other in inches. (Take a compass with you when you buy your ruler so you can pick one that is non-magnetic.) The first thing you do is take some blue painters tape and mask off the inch edge of the ruler. Nothing is worse than using the sixteenths by mistake when you want millimeters. Been there, done that, wore out an eraser.

Know your pace count per 100 meters. Not the running pace count that orienteers use, but walking at your mapping stride. Mine is 61 double paces (count only the left foot) per 100 meters.

Make a simple chart with paces in one column, millimeters (at your map scale) in one column, and meters in a third column. I print out my chart and tape it to my map board. Here is the chart I use. You can look at the formulas and see how I calculate everything.

Now how do you use it? Starting from a boulder that you have already placed correctly(!), count your paces to the next boulder. Use your chart to convert that to millimeters. Use your ruler to measure the distance on your map and make your mark (in the right direction, of course).

You can also use the chart to convert from meters to map millimeters. I sometimes carry a laser rangefinder, which can save a lot of steps. Instead of pacing to the next boulder, I use the gadget to tell me the meters, and convert that to map millimeters using the chart.

Why does the chart round off the millimeters to 0.5? Because you really can’t make a pencil mark smaller than that, and more accuracy is not always a better thing.

Two more good days over the weekend. The weather was cold, but manageable. Finished the bare rock reentrant and crossed the far ridge line. Here the terrain is more eroded. The bare rock seems to have broken apart and left behind large areas of boulder fields. Some of the boulders are house sized. Not McMansion size, but as big as the house I grew up in.

From Chattahoochee Bend

From Chattahoochee Bend

From Chattahoochee Bend

From Chattahoochee Bend

From Chattahoochee Bend

Should be a lot of fun running around in those boulders looking for the right one. There are also more bare rock areas over here where the slope is steeper – something I didn’t expect.

From Chattahoochee Bend

I also found an old homesite with a collapsed chimney and a well. The well is one of the really dangerous kind – at some point GAOC needs to get some volunteers out there to fence it off. Here’s a couple of pictures:

From Chattahoochee Bend

From Chattahoochee Bend

My desire to take photos is inversely proportional to the temperature. The older it is, the less likely I am to fish out the camera, take off my gloves, and record a photo. But the temperature moderated, to a balmy 37 degress, and the sun actually came out for a short time, so I managed to get some photos of he bare rock area that I am currently mapping.

First, the new construction has begun. As always, they make a mess in the process of making something nice. This is the new park road for access to the visitor center. The old road (flat rock road) was dirt and ran right across a portion of bare rock. The new road will swing around to the east and avoid the flat rock.

From Chattahoochee Bend

The flat rock area is becoming clearer now. It is a shallow reentrant, about 300 to 400 meters wide and 800 to 1000 meters long, gently sloping down to the northeast. A reentrant that big is only noticeable on the map – standing there, you cannot tell. It looks like the terrain is either level or sloping away to the northeast. Imagine that it is doted with ponds and lakes, some as small as your living room, others as large as a football field. Now, mentally convert those ponds to bare rock and you have an idea of what it’s like. The vegetation is stunted – I can only guess because the rock is just beneath the surface.

From Chattahoochee Bend

From Chattahoochee Bend

From Chattahoochee Bend

From Chattahoochee Bend

From Chattahoochee Bend

East of the bare rock reentrant, the terrain gets much steeper. Well, steep for Chattahoochee Bend, anyway. The rock has eroded and left huge boulders. More about that in future reports.

Started the next section of the map 12/29/09 after a rest of a few weeks. This section is south of the big powerline and east of Flat Rock road. I picked the coldest morning of the year to do it which called for fingerless gloves. The camera refused to cooperate, even after I warmed up the batteries in an inside pocket, but I went out again the next day and managed to get a few pictures.

From Chattahoochee Bend

From Chattahoochee Bend

This area is very different. The river is far away – no floodplain here. Instead there are low hills, and cutting across those hills are the bare rock areas that gave Flat Rock Road it’s name. I have only barely begun in this section, but already I have learned a few things:

• It’s slow going – lots of detail that needs to be mapped – boulders, bare rock, rootstocks.
• the bare rock area has distinct vegetation. Stunted trees, because the rock is right there beneath the surface even if it is not visible; areas of grass and moss where trees cannot grow; complex patterns of green and white forest.
• the flat rock area is almost like a plateau, probably since it is resistant to erosion. It is deceptively flat, tilted down in a northeast direction.
• There are many more bare rock areas than are visible on the photo. Only the larger ones show up, so the photo is of limited use.
• The lidar contours pick out some of the largest boulders, which is very helpful.

This area will take a while. I know that, once I am off the plateau, there are huge boulders out to the east. I’ve already put more rootstocks in this area than in the entire previous sections, thanks to what must have been a mini-tornado that swirled across the side of one hill.

Construction is on-going on the new road to the visitor center. I am working east of the construction, but I still have to put up with the machine noise. The back-up alarm drives me nuts.

From Chattahoochee Bend

There’s a smiling Kevin on the banks of the river holding the new map. He gave me some valuable help by coming out to cast another pair of eyes over the map. We covered a large portion of the northern map visiting most of the problem areas and discussing how best to represent them on the printed page. The many vegetation changes on this part of the map present the biggest challenge for the mapmaker. The weather was great (and dry) and it was fun to walk back over the map and look at places I hadn’t seen in months.

I’ve decided to divide the remainder of the map into two sections instead of one. Flat Rock road will be the dividing line. I’ll first work east of the road (where most of the rock features are). There are at least 3 sq. km. there. That should take me into the Spring. Then I will venture east of the road, where all of the park construction is happening. That is the largest section, something around 5 sq. km. With any luck and a lot of hard work I should be done in another year, by Christmas 2010 – but don’t hold me to that prediction!

The log of my activity is on the Project Time page, but here is a summary:

238 hours and 15 minutes total time, which includes 151 hours of field checking, 45 hours of drafting, and the rest preparing the base map.

A little over 4 sq km mapped. That’s almost 60 hours per sq km.

30 trips to the park, at 40 miles per trip, equals 1200 total miles of travel.

I started Feb 28 and ended Nov 15.

Now I will take a break. I will start the southern map (which is bigger) in January.