Vienna Basin, Vienna/Lower Austria/Burgenland, in a narrower sense it comprises the triangular basin area south of the River Danube (southern Vienna basin), in a broader sense it is a trench failure system stretching 200 km in length from Gloggnitz in the south to Moravia in the north. Its flanks spread farthest in the middle (55 km in length from Vienna to the Small Carpathian Mountains). The Austrian part of the Vienna basin therefore includes the Marchfeld Plain and the eastern Weinviertel Region as well as the southern Vienna basin. At the beginning of the Upper Tertiary it emerged as a depression area between the Alps and the Carpathian Mountains, in which the sea subsequently deposited up to 5,500 m of sedimentary rock (formation of petroleum deposits). Littoral deposits abundant in fossils can be found on the shores of the former sea (e.g. Leitha Limestone). Earth tremors and various curative springs on the fault line (e.g. Baden, Bad Voeslau and Bad Deutsch-Altenburg) show that geological changes are still occurring. The southern Vienna basin, which forms a depression from southwest to northeast, extends to a width of 60 km between the Wiener Pforte Gap and the Hainburger Pforte Gap and is also limited by the Vienna Woods, Thermenlinie, Semmering Pass, Bucklige Welt, Rosaliengebirge Mountains, Leithagebirge Mountains and the Hundsheimer Berge Hills; The Vienna basin is connected with the area around Lake Neusiedl via the Wiener Neustaedter Pforte Gap and the Brucker Pforte Gap. It is influenced by the Pannonian climate. The Vienna basin can be divided into 4 smaller areas: 1) Hills and tableland can be found to the south of the River Danube; the loess-covered gravel plates are fertile soil used for agriculture, and the gravel hills are either wooded or used for wine growing (e.g. Rauchenwarther Platte and Ellender Wald area); after Vienna, Schwechat (Vienna Airport) and Bruck an der Leitha are the most important municipalities. 2) The "Wet Plain" (area of intensive farming, fruit growing and horticulture) ranges from the southern edge of the gravel plates to the Ebreichsdorf area. Municipalities: Ebreichsdorf and Mitterndorf an der Fischa (Mitterndorfer Senke Depression). 3) In the west, the "Wet Plain" fades into a fringe zone characterised by wine growing, situated alongside the Thermenlinie fault line. Municipalities: Perchtoldsdorf, Brunn am Gebirge, Maria Enzersdorf am Gebirge, Moedling, Gumpoldskirchen, Pfaffstaetten, Baden and Bad Voeslau (health resorts with thermal springs). 4) In the southeast, the "Wet Plain" is followed by the Steinfeld area, a region with thin, low-quality soil which was reafforested with pine trees in the 18th century; principal town: Wiener Neustadt. The main waters of the Vienna basin are the rivers Schwarza, Pitten, Leitha, Fischa, Piesting, Triesting and Schwechat as well as the Wiener Neustadt Canal. The Vienna basin is one of the most important industrial areas in Austria, boasting industries such as chemical and plastics (refinery in Schwechat), metal processing, textile and clothing, quarry and pit, glass, food and paper as well as related services and retail trade ( Shopping-City Sued). There are important research institutions in Laxenburg (International Institute for Applied Systems Analysis) and Seibersdorf (Forschungszentrum Seibersdorf GmbH). Some parts of the Vienna basin are among the most densely populated regions in Austria: The population density in permanently inhabited areas amounts to a number of 500-1000 or 1000 and more inhabitants per km2 next to the main traffic artery. The western edge of the Vienna basin is made accessible through the Sued-Autobahn motorway (A 2), the Triester Strasse Road, the Southern Railway and the Schnellbahn suburban service, which terminates at Wiener Neustadt; Baden can be reached via the Badner Bahn suburban service. The part of the Vienna basin next to the Danube is accessible via a branch line of the Eastern Railway, the Schnellbahn suburban service to Wolfsthal and the A 4 motorway towards Bruck an der Leitha. Eisenstadt can be reached on the A 3 motorway and the Federal Road 16; there are also a number of short-distance railway lines and roads in the Vienna basin.