Question: During what period did the mountain range in which Isoetes valida is primarily found first form?
Context: The Coast Mountains are a major mountain range in the Pacific Coast Ranges of western North America, extending from southwestern Yukon through the Alaska Panhandle and virtually all of the Coast of British Columbia south to the Fraser River.  The mountain range's name derives from its proximity to the sea coast, and it is often referred to as the Coast Range.  The range includes volcanic and non-volcanic mountains and the extensive ice fields of the Pacific and Boundary Ranges, and the northern end of the volcanic system known as the Cascade Volcanoes.  The Coast Mountains are part of a larger mountain system called the Pacific Coast Ranges or the Pacific Mountain System, which includes the Cascade Range, the Insular Mountains, the Olympic Mountains, the Oregon Coast Range, the California Coast Ranges, the Saint Elias Mountains and the Chugach Mountains.  The Coast Mountains are also part of the American Cordilleraa Spanish term for an extensive chain of mountain rangesthat consists of an almost continuous sequence of mountain ranges that form the western backbone of North America, Central America, South America and Antarctica. Zorite is a silicate mineral with the chemical formula of NaTi(Si,Al)O·nHO.  It is named because of its pink color, after the Russian word "zoria" which refers to the rosy hue of the sky at dawn.  It is primarily found in Mount Karnasurta, Lovozero Massif, Kola Peninsula, Russia.  The Lovozero Massif is an area with an igneous mountain range, home to various types of minerals such as eudialyte, loparite, and natrosilitite. The Haiyang Mountains (), in ancient times known as ""Yanghai Mountains"" () form a mountain range in the northeastern Guangxi separating West River drainage basin of the Xi River from the Xiang River drainage basin of the Yangtze River.  The mountain range is located between Yuecheng Mountains and Dupang Mountains of Nanling Mountain Range, it is a major mountain range in Guilin, Guanxi, China.  It runs south to north through Guanyang, Quanzhou, Xing'an, Lingchuan, Gongcheng and Yangshuo six counties.  With a width of 35 km to 40 km , the Haiyang Mountains stretch more than 97 km from Yangshuo to Quanzhou.  The highest peak is "Baogai Hill" (宝界岭) with an elevation of 1935.8 m . The rufous-crowned sparrow ("Aimophila ruficeps") is a small American sparrow.  This passerine is primarily found across the Southwestern United States and much of the interior of Mexico, south to the transverse mountain range, and to the Pacific coast to the southwest of the transverse range.  Its distribution is patchy, with populations often being isolated from each other.  Twelve subspecies are generally recognized, though up to eighteen have been suggested.  This bird has a brown back with darker streaks and gray underparts.  The crown is rufous, and the face and supercilium are gray with a brown or rufous streak extending from each eye and a thick black malar streak. Crocker Range (Malay: "Banjaran Crocker" ) is a mountain range in Sabah, Malaysia.  It is named after William Maunder Crocker.  The mountain range separates the east coast and west coast of Sabah.  At an average height of 1800 m , it is the highest mountain range in Sabah.  Mount Kinabalu, one of the highest mountains in Southeast Asia, is part of this range.  Part of the range has been gazetted for protection as Crocker Range Park since 1984.  The area surrounding Mount Kinabalu has been a state park since 1964 and was the country's first World Heritage Site. The Gamburtsev Mountain Range (also known as the Gamburtsev Subglacial Mountains) is a subglacial mountain range located in East Antarctica, just underneath the lofty Dome A, near the Southern Pole of Inaccessibility.  The range was discovered by the 3rd Soviet Antarctic Expedition in 1958 and is named for Soviet geophysicist Grigoriy A. Gamburtsev.  It is approximately 1200 km long, and the mountains are believed to be about 2700 m high, although they are completely covered by over 600 m of ice and snow.  The Gamburtsev Mountain Range is currently believed to be about the same size as the European Alps, and, as of 2008, it is unknown how the mountains were formed, though the current speculated age of the range is over 34 million years and possibly 500 million years.  Current models suggest that the East Antarctic ice sheet was formed from the glaciers that began sliding down the Gamburtsev range at the end of the Eocene.  Vostok Subglacial Highlands form an east extension of Gamburtsev Subglacial Mountains. Isoetes valida, commonly known as the strong quillwort or true quillwort, is an aquatic pteridophyte native to eastern North America.  It is found primarily in the Appalachian Mountains from Pennsylvania south to Alabama and Georgia.  In addition, one collection of the plant was made in a railway ditch in Wilmington, Delaware in the 1860s, but this was most likely an accidental introduction. Mingli Sar is a mountain located in the Shimshal valley in Gilgit-Baltistan, Pakistan.  The mountain, located in the Karakoram mountain range, is 6050 meters high and located at the southernmost part of the Pamir mountain range.  It was first climbed in 1988 by the famous Pakistani climber Nazir Sabir.  Shimshal lake sits at the base of the mountain.  China is located to the north, while to the left is the Hindukush mountain range.  K2 is located on the south eastern side of the valley. The Appalachian Mountains ( , French: "les Appalaches" ), often called the Appalachians, are a system of mountains in eastern North America.  The Appalachians first formed roughly 480 million years ago during the Ordovician Period.  It once reached elevations similar to those of the Alps and the Rocky Mountains before naturally occurring erosion.  The Appalachian chain is a barrier to east-west travel, as it forms a series of alternating ridgelines and valleys oriented in opposition to most roads running east or west. The Zagros Mountains (Persian: رشته كوه زاگرس‎ ‎ , Kurdish: زنجیره‌چیای زاگرۆس‎ ; "Çiyayên Zagrosê", Lurish: کۆیەلی زاگروس, Syriac: ܛܘ̣ܪܵܢܹܐ ܕܙܵܓܪܘ̇ܣ‎ , Arabic: جبال زغروس‎ ‎ Aramaic: ܛܘܪ ܙܪܓܣ,) form the largest mountain range in Iran, Iraq and southeastern Turkey.  This mountain range has a total length of 1,500 km (932 mi).  The Zagros mountain range begins in northwestern Iran and roughly corresponds to Iran's western border, and it spans the whole length of the western and southwestern Iranian plateau, ending at the Strait of Hormuz.  The highest point in the Zagros Mountains is Dena.
Answer: the Ordovician Period