Let’s see what’s in the line up for Good Articles in geology, articles which may eventually appear on Wikipedia’s main page.
“Glastonbury Tor is a hill at Glastonbury in the English county of Somerset, ….
The conical hill of clay and Blue Lias rises from the surrounding Somerset Levels. It was formed when surrounding softer deposits were eroded, leaving the hard cap of sandstone exposed.
Location and landscape
The Tor consists of layers of various Lias Group strata of early Jurassic age, the uppermost of which are the rocks assigned to the Bridport Sand Formation and which overlie strata of the Beacon Limestone Formation and Dyrham Formation. The Bridport Sands have acted as a caprock protecting the lower layers from erosion. The iron-rich waters of Chalice Well, a spring, flow out as an artesian well impregnating the sandstone around it with iron oxides that have reinforced it. Iron-rich but oxygen-poor water in the aquifer carries dissolved iron (II) “ferrous” iron, but as the water surfaces and its oxygen content rises, the oxidized iron (III) “ferric” iron drops out as insoluble “rusty” oxides that bind to the surrounding stone, hardening it.”
A hill of clay and Blue Lias. Good so far, but the next sentence says it is capped by sandstone. Problematically, Blue Lias is a well known limestone and shale formation; but, I’m not all that familiar with European formations, and I can just check the handy wikilinked article on Blue Lias to confirm there is some sandstone in it.
“The Blue Lias consists of a sequence of limestone and shale layers, laid down in latest Triassic and early Jurassic times, between 195 and 200 million years ago. The Blue Lias is famous for its fossils, especially ammonites.”
Inconclusive, as we’ve seen how well Wikipedia does geology–often not well at all. Two geology articles contradicting each other on Wikipedia are nothing new. The Lias Group is rather large, there must be some sandstone in it. Clicking on that link, we learn that the Blue Lias is under- and overlain by shales.
We opened the article with the hill being from some uncontained and unknown clays, and the Blue Lias Formation, and then, as we go into the article, we’ve expanded, greatly, the range of the stratigraphy in the hill to the Lias Group. We learn that the uppermost Lias Group formation is the Bridport Sand Formation. (By the way, the Wikipedia article on the Lias Group also points out that it is not Early Jurassic, but is Late Triassic to Early Jurassic.) The Lias Group article does not mention the Bridport Sand Formation. the Beacon Limestone Formation or the Dyrham Formation. I will look at the source, .
“Somerset’s famous landmark, Glastonbury Tor, is made up of Bridport Sand Formation on Beacon Limestone Formation on Dyrham Formation; the latter also forming Wearyall OR/12/032; Final 1.1 3 Hill west of the Tor.”
This is the description of the formations and geology within the Wessex Basin, where Somerset is, geologically. And, let’s look at the geology of the Wessex Basin from the source.
Wessex Basin and Bristol Channel Basin
“The entire Lias succession is well exposed on the Dorset coast between Lyme Regis and Burton Bradstock (Callomon and Cope, 1995; Hesselbo and Jenkyns, 1995). As now classified (Cox et al., 1999) it comprises:
Bridport Sand Formation
Beacon Limestone Formation
Charmouth Mudstone Formation
Blue Lias Formation”
Is the hill Blue Lias Formation, or is it upper Lias Formation, or is it some made up Wikipedia-can’t-read-the-geology formation? And where’s the clay?
What is a tor, by the way?
According to the geological article on Wikipedia on tors, a “tor is a large, free-standing residual mass (rock outcrop) that rises abruptly from the surrounding smooth and gentle slopes of a rounded hill summit or ridge crest.” That does sound about right.
According to this article on the Glastonbury Tor, “tor is an English word meaning a high rock or a hill, deriving from the Old English torr.[note 1]”
While the latter may technically be correct, this article does wikilink to the geological article on tor; so, again, we have contradictory meanings. The residual nature of a tor, found in the geological definition on Wikipedia is important; it gives some small group of readers information to read further and encounter the word again and place an object in its geological context; it gives another group of readers, those with backgrounds in geology, an instant visualization of the object. It’s also a fun word.
What gives Wikipedia? What is a Good Article, anyway, and how can you come up with them, if your editors can’t read basic geological articles and won’t read other Wikipedia articles they link to?