Tamacha appears to have been, or still is, a village, there are some buildings that might be of recent construction. I haven't found anything yet on a place named Tamacha in Botswana.
I have now read your link “Wind as a Geologic Agent.” The parallel lines visible on the Google Earth map do NOT have the characteristics of any of the dune processes shown. They have two slightly raised lines with a narrow sunken area between, or two slightly raised lines with a wide flat area between. In other words, the progression is raised, narrow sunken, raised, wide flat, raised, narrow sunken, raised, wide flat, raised, narrow sunken, raised, wide flat, etc. etc. etc. for dozens or more repetitions. Where are there any generally accepted as natural dune features like that??? In addition the ridges are not high like dunes tend to be especially when spaced that far apart. Look at the Google Map link at Comment 48. Go in close, 100 and 200 feet. Look at a lot of them in different areas. No high dunes, and always the wide, narrow, wide, narrow pattern.
I have given the whole issue more thought. Since this is a seasonally heavily watered area, and even more so in the past, the ground must be mostly silt and organic matter, many feet deep. Thus, no rocks for building, thus no human artifacts that might be 7000 to 14,000 years old. The nearest recognized large stone feature is Great Zimbabwe to the east. Very little is known about that feature. Obviously, archaeologists need to get in there and spend a lot of time tying the region together developmentally. From what I could see of existing structures, they are rectangular enclosures, probably brush, and round, small huts, often not on what are probably agricultural efforts in the “canals”, but up on the “ridges.” I will need to look in other areas to see if the pattern is the same. Most of what I look at was in the area between Etosha and the Okavango River.
Tamacha appears to have been, or still is, a village, there are some buildings that might be of recent construction. I haven't found anything yet on a place named Tamacha in Botswana.
Laurens van der Post panel, 2006
The Tsodilo Hills are a UNESCO World Heritage Site (WHS), consisting of rock art, rock shelters, depressions, and caves. It gained its WHS listing in 2001 because of its unique religious and spiritual significance to local peoples, as well as its unique record of human settlement over many millennia. UNESCO estimates that there are over 4500 rock paintings at the site. The site consists of a few main hills known as the Child Hill, the Female Hill, and the Male Hill. These hills are of great cultural and spiritual significance to the San of the Kalahari.
I'd love to ask Caterpillar to determine the amount of earth which has been displaced in these formations, then to calculate how many D-9 Cats & self-loading Pans would be required working "X" number of years to complete this project.
Just the total area covered, the minimal elevation change over that area and the regularity of spacing & azimuth is absolutely astounding!
Perhaps an interstellar version of a combination of these two? /S
Thanks glee’. The whole formation is fairly uniform, and spread out over such a large area, that it is bound to be natural, because it would otherwise be tremendously extravagant of labor, not to mention that it would have been done to address a lack of water, and that characteristic doesn’t correlate with a large population capable of constructing it over such a large area. One of the papers someone up there linked had the steps needed to produce what is seen, and it seemed plausible. The nearby delta used to drain into a now-vanished lake, and these straight-line formations are seen on both sides. This isn’t to say that it could not be artificial, just that one would expect different areas of it to be more eroded because it is older, with a smallish population gradually moving to find fertile soil and abandoning former areas.
“The parallel lines visible on the Google Earth map do NOT have the characteristics of any of the dune processes shown. They have two slightly raised lines with a narrow sunken area between, or two slightly raised lines with a wide flat area between. In other words, the progression is raised, narrow sunken, raised, wide flat, raised, narrow sunken, raised, wide flat, raised, narrow sunken, raised, wide flat, etc. etc. etc. for dozens or more repetitions. Where are there any generally accepted as natural dune features like that???”
You are badly mistaken. One of the illustrations correctly describes how bidirectional winds form longitudinal dunes that tend to merge into the so-called linear dunes. What you fail to understand is your misperception of the Google images due to optical illusions and the degraded nature of the ancient dunes which are now represented by little more than consolidated soils with gentle rises and dips in a generally flat landscape. What you are misperceiving as canals is due in great part to the coloring of the soils by the sorting of the soils in the remnant bases of the dunes and valleys between the dunes, embayment of moisture between the slight rises, and coloration due to the plant life exploiting moisture and their contribution of material to color the soils. When you drive across those so-called stripes you misperceive as canals, you will be hard put to find evidence of a canal. Instead, you are seeing the remnants of the soils after 30,000 to 60,000 years of dune and other erosion and the formation of topsoils in an arid environment.
“In addition the ridges are not high like dunes tend to be especially when spaced that far apart.”
You wouldn’t expect them to be so. The dunes were relatively broad and low to begin with, and tens of thousands of years of erosion and degradation have reduced them to some very low rolling terrain covered in vegetation that stabilized the soils and colored them in the subsequent millennia.
“Look at the Google Map link at Comment 48. Go in close, 100 and 200 feet. Look at a lot of them in different areas. No high dunes, and always the wide, narrow, wide, narrow pattern.”
Try driving on the road across those dune stripes. Geological samples have been taken from inside the linear dunes. Can you even manage to see the dunes and valleys from the road? What you think you see in the Google satellite views are illusions which disappear when you look at them from closeup on the ground.
Near the Okavango Delta. They appear to have a spatial frequency of about 1 mile and cover thousands of square kilometers...
Those are the dunes of the Kalahari desert.
The northern dune field is characterised by broad linear dunes of approximately 25 m high and 1.5 to 2 km apart and extending as much as 200 km (Grove, 1969; Lancaster, 1980). Degradation of the dunes in this field increases towards the north (Flint and Bond, 1968; O’Connor and Thomas, 1999). The eastern field is characterised by degraded linear dunes with up to 50 km of unbroken length (Flint and Bond, 1968) and by barchan dunes and transverse dunes to the west of Makgadikgadi (Grove, 1969; Mallick et al., 1981).
Helgren and Brooks (1983) suggested that the large linear dunes were formed during the Early Pleistocene or late Tertiary and Cooke (1980) suggested deposition of the sands during intervals of Lower-Mid Pleistocene aridity. Although several other dates for conditions favouring dune formation have been suggested by various other workers (e.g. Lancaster, 1981, Van Zinderen Bakker, 1982, Deacon et al., 1984; Heine, 1981, 1982, 1990) there were not many absolute dates for the formation of dunes other than a dune-base peat date of 19 680 ± 100 years BP in the Makgadikgadi (Thomas and Shaw, 1991a) and a powder calcrete within a dune near Etosha dated at 3 510 BP (Rust,1984).
And there we seem to have it. It's been an interesting journey.