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40-637: The Klondike Mountain formation is the youngest in a series of formations which belong to the Challis Sequence volcanics, and is the southernmost of the Eocene Okanagan Highlands paleolake lagerstätten. The formation unconformably overlies rocks of the Eocene Sanpoil Volcanics and much older Triassic and Permian formations. The formation is bounded on its edges by a series of high-angle strike slip faults , which have contained

80-417: A 1992 Washington Geology paper on the conifer research at Republic. The name was derived from the current Okanagan Highlands but applied to the, as then identified, microthermal forests preserved at Republic and Princeton. The term was expanded upon, and by 2005 it was generally understood to encompass all Eocene fossiliferous formations between Republic and Smithers, British Columbia . The highlands as

120-490: A diverse mix of temperate and tropical paleobiotic elements, with the forests having the first significant proportions of temperate plants in North America. The paleobotanical community was a mixture of plants found in subtropical evergreen and temperate deciduous forests . Included in the forest were a number of important modern temperate flowering plant families such as Betulaceae , Rosaceae , and Sapindaceae , plus

160-412: A group of sites was by Glenn E. Rouse and William H. Mathews (1961) who tested biotite samples from four locations. They sampled volcanic ashes from Princeton and Rock Creek; a Trachyte flow from Savona Mountain and a diabase flow or sill from Tranquille, returning results of 49 to 45 million years ago , then classified as Early Middle Eocene. They noted the very distinct similarities with

200-463: A highly diverse and detailed plant and animal paleobiota the paleolake beds as a whole are considered one of the great Canadian Lagerstätten . The paleobiota represented are of an upland subtropical to temperate ecosystem series immediately after the Paleocene–Eocene thermal maximum , and before the increased cooling of the middle and late Eocene to Oligocene. The fossiliferous deposits of

240-544: A later written communication circa 1958, Brown again revised the age still older, stating the fossils found in the area of Mount Elizabeth indicated an Oligocene age. This age was used by Parker and Calkins (1964) for work on the Curlew Quadrangle of Ferry County. Work by Pearson and Obradovich (1977) refined the Sanpoil Volcanics age to around 52 to 51 million years ago , and a general age estimate for

280-600: A mean annual temperature of approximately 8.0 °C (46.4 °F), while the LMA gave 9.2 ± 2.0 °C (48.6 ± 3.6 °F). This is lower than the mean annual temperature estimates given for the coastal Puget Group, which is estimated to have been between 15 and 18.6 °C (59.0 and 65.5 °F). The bioclimatic analysis for Republic suggests a mean annual precipitation amount of 115 ± 39 cm (45 ± 15 in). The Klondike Mountain Formation

320-472: A series of papers on the plants, authored by John William Dawson , later David Pearce Penhallow and Edward Wilber Berry . The insects were first detailed by Samuel Hubbard Scudder , with follow-up papers by Anton Handlirsch . While reporting on additional plant fossils collected from British Columbia, Penhallow (1906) noted the likely coeval status of the Princeton basins with many of the sites now considered

360-468: A transition to mudstones , siltstones and sandstones grading from fine-grained material into coarser materials moving up the strata column. The finely-bedded stones show the greatest numbers of fossils and the finest preservation of details. The lake bed sediments preserve a diverse array of plants, insects, and fishes, notably the biota called the Republic flora . The Okanagan lake system, which includes

400-687: A whole have been described as one of the "Great Canadian Lagerstätten " based on the diversity, quality and unique nature of the biotas that are preserved. The highlands temperate biome, preserved across a large transect of lakes, recorded many of the earliest appearances of modern genera, while also documenting the last stands of ancient lines. The majority of formations in the Eocene Okanagan Highlands preserve compression fossils in sandstone to shale rock deposited from lake environments where seasonal mixing and anoxia were prevalent. Additionally, two important non-compression biotas are present in

440-443: Is host to a highly diverse assemblage of plants and insects including some of the last records of taxa before extinction and the first appearances of taxa. Eocene Okanagan Highlands The Eocene Okanagan Highlands or Eocene Okanogan Highlands are a series of Early Eocene geological formations which span a 1,000 km (620 mi) transect of British Columbia , Canada, and Washington state , United States. Known for

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480-429: Is lower than the mean annual temperature estimates given for the coastal Puget Group, which is estimated to have been between 15–18.6 °C (59.0–65.5 °F). The bioclimatic analysis for Republic and Princeton suggest mean annual precipitation amounts of 115 ± 39 cm (45 ± 15 in) and 114 ± 42 cm (45 ± 17 in) respectively. The warm temperate uplands floras of

520-656: Is particles of rock derived from pre-existing rock through weathering and erosion . A fragment of detritus is called a clast . Detrital particles can consist of lithic fragments (particles of recognisable rock), or of monomineralic fragments (mineral grains). These particles are often transported through sedimentary processes into depositional systems such as riverbeds, lakes or the ocean, forming sedimentary successions. Diagenetic processes can transform these sediments into rock through cementation and lithification , forming sedimentary rocks such as sandstone. These rocks can then in turn again be weathered and eroded to form

560-660: The "Driftwood shales" near Smithers, British Columbia , and the " Horsefly shales ", of an unnamed formation and unnamed group which outcrop around Horsefly, British Columbia . The Central sites represent Kamloops Group formations with the McAbee Fossil Beds , Tranquille River site and Falkland site , all in the Tranquille Formation , the Quichena site and Stump Lake site in the Coldwater Beds and outcrops of

600-764: The Chu Chua Formation near Barriere, British Columbia . The Southern sites include the Princeton Group Allenby Formation sites surrounding Princeton, British Columbia , such as "Nine Mile Creek", "One Mile Creek", "Pleasant Valley", "Thomas Ranch", "Vermilian Bluffs", and "Whipsaw Creek". The most southerly of the Okanagan Highlands lakes, the Klondike Mountain Formation in Northern Ferry County, Washington , include

640-655: The Florissant Formation of Colorado, which at the time was also considered Miocene. This age was retained by Edward W. Berry (1929), who included the Klondike Mountain Formation fossil lakebeds as part of the Latah Formation . The age of the Formation has been revised in the following hundred years, with Roland W. Brown (1936) identifying the deposits as being older than the Latah Formation. In

680-542: The Latah Formation . The inclusion within an expanded Latah Formation was questioned by Roland W. Brown in 1936, who noted the similarities between Republic and other older fossil sites, combined with the Republic lake bed's overlying basalts then thought to be of similar age to the Columbia River Basalts . This similarity was again noted by Chester A. Arnold during his review of the conifer flora associated with

720-688: The "Boot Hill site", "Corner Lot site", "Gold Mountain site", "Knob Hill site", and "Mount Elizabeth site". Closely correlated with the Klondike Mountain Formation are the Penticton groups Kettle River , Marama and Marron Formations in the Boundary District along the Canada–United States border. There is debate as to the affiliation of the, now lost, Quesnel sites with the Greater Okanagan Highlands. Archibald et al (2018) in

760-853: The Eocene Okanagan Highlands: A permineralized chert flora, the Princeton Chert is found along the Similkameen River interbedded with coal deposits of the Ashnola shale unit, Allenby Formation, known for anatomically preserved plants. In the Central sites, subbituminous coal of the Hat Creek Coal Formation around Hat Creek hosts an amber fauna, the Hat Creek amber which preserves many small insects that would likely not be found in

800-400: The Formation's lowest unit. Hydrothermal sinter deposits are known from the lowest portions of the Formation and are thought to represent hydrothermal eruption areas. In general the lower portions of the Formation have a large amount of hydrothermal alteration , and areas around vents are rich in pyrite and silica . two products of natural hydrothermic sintering. The areas above that show

840-667: The Klondike Mountain Formation are the Penticton Group 's Kettle River , Marama and Marron Formations in the Boundary District along the Canada-United States border. Early dating of the formation was based primarily on identification and correlation of the fossils found in the Tom Thumb Tuff, with Joseph Umpleby (1910) reporting a putative age of Early Miocene . This date was based in examination of fossils by C. R. Eastman, who thought them to be similar to those found in

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880-624: The Klondike Mountain Formation between 50.3  ± 1.7 million years ago and 42.3  ± 2.0 million years ago . Since then the fossil-bearing strata of the Formation have been radiometrically dated , to give an estimate of the Ypresian , the mid stage of the early Eocene, 49.4  ± .5 million years ago , which was revised to an oldest age estimate of 51.2  ± 0.1 million years ago which given based on detrital zircon isotopic data published in 2021. Parker and Calkins (1964) noted

920-527: The Klondike Mountain Formation in a series of graben structures, such as the Republic Graben . Public access to a fossiliferous outcrop at the north end of Republic is mediated by the nonprofit Stonerose Interpretive Center . The formation is located in northern Ferry County, Washington , with the majority of the sedimentation in the Republic and Curlew Basins on the east and in the Toroda Creek area to

960-482: The Klondike Mountain Formation, has been classified as one of the great Canadian lagerstätten . The area likely had a mesic upper microthermal to lower mesothermal climate, in which winter temperatures rarely dropped low enough for snow, and which were seasonably equitable. The Okanagan highlands paleoforest surrounding the lakes have been described as precursors to the modern Temperate broadleaf and mixed forests of Eastern North America and Eastern Asia. Based on

1000-604: The Okanagan Highlands. The first brief work on fish from the Highlands occurred with the 1893 report by Edward Drinker Cope on several fish sent to him by George Dawson from the Tranquille and Princeton areas. While Cope deemed the Tranquille specimens too incomplete to identify, he did provide the description for "Amyzon" brevipinne from the Similkameen River fossils. Republic, Washington , area fossils were first reported by Joseph Umpleby (1910), based on fish he collected near

1040-481: The Princeton and Republic paleofloras. The CLAMP results, after multiple linear regressions for Republic, gave a mean annual temperature of approximately 8.0 °C (46.4 °F), while the LMA gave 9.2 ± 2.0 °C (48.6 ± 3.6 °F). Princeton's multiple linear regression CLAMP results gave a slightly lower 5.1 °C (41.2 °F), and the LMA returned a mean annual temperature of 5.1 ± 2.2 °C (41.2 ± 4.0 °F). This

1080-527: The Princeton basin. Arnold noted the Allenby sites shared over half of the taxa that had been previously reported from Republic. Starting in the early 1960s and extending through the 1980s were a series of papers on the British Columbian sites combining palynology and the newly devised process of potassium–argon dating to better understand the geochronology of the sites. The first report of K–Ar dating at

1120-510: The Republic flora, as Arnold had, and posited that the Republic fossils were of the same age, and not Oligocene as then considered. Based on the estimated age, the sites were noted to be coeval with the Green River Formation but that the floras of the two regions were drastically different, and that more study was needed. The term "Okanagan Highlands" for Eocene formations of the region was coined by Wesley Wehr and Howard Schorn in

1160-476: The Tom Thumb mine, and given a tentative late Miocene age. Two of the fish were figured and briefly mentioned 7 years later by Charles R. Eastman , who assigned them tentatively to "Amyzon" brevipinne , making one of the early connections between Republic and the British Columbian sites. Report of the plant fossils of the Republic area were first published by Berry (1929) who included the Republic fossils as part of

1200-510: The association of the Klondike Mountain Formation with the gold and silver deposits of the Republic District and suggested it as a potential host to more ore deposits in the Curlew Quadrangle. The epithermal gold deposits occurring in the Sanpoil volcanics terminate directly below the unconformity where the volcanics contact the base of the Klondike Mountain Formation or sometimes penetrate into

1240-409: The compression biotas. Based on paleobotanical proxies and geochemical data, the highlands are thought to have been between 500–1,500 m (1,600–4,900 ft) in elevation, placing them similar to or higher than the modern sites. Estimates of the mean annual temperature have been derived from climate leaf analysis multivariate program (CLAMP) analysis and leaf margin analysis (LMA) of both

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1280-544: The conifer family Pinaceae . Study of the deciduous plants from the highlands has documented the occurrence of heteromorphic leaves derived from sun versus shade conditions and long shoot or short shoot buds. The paleobotanical community of the Republic area has been noted as the most diverse floral community of the Okanagan Highlands, with some estimates ranging to over 68 families and 134 genera being present. Detrital Detritus ( / d ə ˈ t r aɪ t ə s / ; adj. detrital / d ə ˈ t r aɪ t əl / )

1320-457: The fossil biotas the lakes were higher and cooler then the coeval coastal forests preserved in the Puget Group and Chuckanut Formation of Western Washington, which are described as lowland tropical forest ecosystems. Estimates of the paleoelevation between 0.7 and 1.2 km (0.43 and 0.75 mi) higher than the coastal forests. This is consistent with the paleoelevation estimates for

1360-619: The highlands, associated with downfaulted lacustrine basins and active volcanism are noted to have no exact modern equivalents, due to the more seasonally equitable conditions of the Early Eocene. However, the highlands have been compared to the upland ecological islands in the Virunga Mountains within the Albertine Rift of the African rift valley . The Eocene Okanagan Highlands hosted

1400-416: The lake systems, which range between 1.1 and 2.9 km (1,100 and 2,900 m), which is similar to the modern elevation 0.8 km (0.50 mi), but higher. Estimates of the mean annual temperature have been derived from Climate leaf analysis multivariate program (CLAMP) and leaf margin analysis (LMA) of the Republic paleoflora. The CLAMP results after multiple linear regressions for Republic gave

1440-655: The leadership of George Mercer Dawson in the mid-1870s to document the coal and mineral resources of British Columbia. During the 1875 field work, fossil collections were made in the Quesnel region. Two years later, in 1877, the expedition explored the Okanagan, Nicola, and North Thompson valleys with field collecting along areas of the Similkameen River , Whipsaw Creek and Nine-Mile Creek, north at around Quilchena, and at several areas near Kamloops. These expeditions resulted in

1480-489: The monograph overview of the Highlands Hymenoptera included them as part of the series. However the certainty for the placement was later questioned by Archibald and Cannings (2022) who opted to tentatively exclude Quesnel from the highlands while discussing the history of field collecting in the region. The earliest geological work in south and central British Columbian sites was during exploratory expeditions under

1520-467: The north west. The town of Republic, Washington is situated at the southern end of the formation, with outcrops within the city itself. The formation was named for Klondike Mountain which is just to the northeast of the city, and where the type locality is located. The Curlew basin is situated north of Republic, with the northern edge along the Kettle River and the community of Curlew, Washington near

1560-418: The northeastern edge. The formation is the southernmost of in the string of Eocene highland lakebeds that extend into British Columbia . The lake system, overlapping the modern Okanagan highlands , extends from the Klondike Mountain Formation northwest approximately 1,000 kilometres (1,000,000 m) in to central British Columbia. Closely correlated with and possibly representing the same lake sequence as

1600-643: The region were noted as early as 1873, with small amounts of systematic work happening in the 1870–1920s on British Columbian sites, and 1920–1930s for Washington sites. Focus and more detailed descriptive work on the Okanagan Highland sites started in the late 1960s. The majority of the paleolake deposits are compression fossils in lake bed sediments spanning a 1,000 km (620 mi) transect, which have been grouped informally into "Northern", "Central", and "Southern" sites. The Northern sites are composed of unnamed Ootsa Group formations which outcrop as

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