Hegau in the context of "Natrolite"

Ultramafic rocks (also referred to as ultrabasic rocks, although the terms are not wholly equivalent) are igneous and meta-igneous rocks with a very low silica content (less than 45%), generally >18% MgO, high FeO, low potassium, and are usually composed of greater than 90% mafic minerals (dark colored, high magnesium and iron content). Earth's mantle is composed of ultramafic rocks. Ultrabasic is a more inclusive term that includes igneous rocks with low silica content that may not be extremely enriched in Fe and Mg, such as carbonatites and ultrapotassic igneous rocks.

Gailingen am Hochrhein (pronounced [ˈɡaɪlɪŋən ʔam ˈhoːxʁaɪn], lit. 'Gailingen on the High Rhine'; Low Alemannic: Gailinge am Hochrhi) is a village in the district of Konstanz in Baden-Württemberg, in southern Germany.

It is situated in a southernmost part of the region of Hegau in a unique location on the northern bank of the High Rhine, just across the border from Switzerland and close to Lake Constance. Its population is currently 3,070.

Hohenstoffeln is a double peaked mountain of volcanic origin in the Hegau region (Konstanz district) of southern Baden-Württemberg, Germany.

Hohentwiel (German pronunciation: [ˈhoːənˌtviːl] ) is a mountain of volcanic origin in the Hegau region of Baden-Württemberg in southern Germany. It is the Hausberg of the industrial city of Singen, located west of it and ca 10 km (6.2 mi) west of Zeller See (Lake Constance). The ruins of the medieval Hohentwiel Castle rest on top of it.

Hohentwiel was an active volcano about 7–8 million years ago during the Miocene epoch, along with several other volcanoes in the Hegau region. It mostly consists of phonolite, which represents the former volcanic pipe. The surrounding softer rocks have been eroded over time by ice age glaciers during the Riss glaciation, creating an inverted relief and giving the mountain its present-day shape.

The term Albtrauf (Alp escarpment) refers to the northwest facing escarpment of the Swabian Alps, situated in Baden-Württemberg and Bavaria. It is the most distinctive stepped slope within the alpine region of the South German Scarplands, leading roughly from the southwest to the northeast.

The Albtrauf has its geological extension in the northeast, in the stepped slopes of the Franconian Jura and in the southwest and west among the Jurassic period stepped slopes of the Baaralb, Hegaualb, Randen, Klettgau, Aargau as well as the Table Jura stretches from the city of Basel to the Ajoie and the French Scarplands.

Hnabi or Nebi (c. 710 – c. 789) was an Alemannian duke. He was the son of Huoching and perhaps a grandson of Duke Gotfrid, which would make him a scion of the Agilolfing dynasty of Bavaria. He was the founder of the "old" line of the Ahalolfings. Around 724, he was one of the joint founders of the monastery of Reichenau.

By his wife Hereswind (Hereswintha) von Bodensee, Hnabi left at least two children, Ruadbert (Rodbert, Robert), who was count in the Hegau, and Imma or Emma (died c. 785), who married Gerold of Anglachgau and was the mother of Eric of Friuli and Hildegard, wife of Charlemagne. Rodbert son of Hnabi is mentioned in a St. Gall document dated 770. Imma is mentioned in documents of Lorsch, Fulda and St. Gall between 779 and 804.