Cascadero Falls is a waterfall on the Finlay River in the Northern Interior of British Columbia, Canada, located just below that river's head at the outlet of Thutade Lake.
 The height of the falls is 180 ft and below it there are numerous cascades or rapids in a twisting course prior to the river's general northeastward trend from this area.
 The falls are slated for hydroelectric development in connection with the area's mines, the largest of which is the Kemess Mine owned by Northgate Minerals Inc., located just east of the foot of Thutade Lake in the valley of Kemess Creek.
The Thompson-Lundmark Mine was a gold producer in the periods 1941–1943 and 1947–1949, near Yellowknife, Northwest Territories.
 Gold was discovered here in 1938 by Fred W. Thompson and Roy Lundmark; they staked 46 claims that were incorporated into the mine.
 Underground and shaft work began in 1939.
 The mine processed 133,989 tons of ore to produce 70,339 troy ounces (2188 kg) of gold and 13,782 troy ounces (429 kg) of silver.
 The abandoned site was destroyed by forest fires during 1998.
 A detailed history is available in the link below.
Cairnbrook Historic District is a national historic district located at Shade Township in Somerset County, Pennsylvania.
 The district includes 132 contributing buildings and 8 contributing structures.
 It encompasses an area developed by the Loyal Hanna Coal and Coke Company of Philadelphia, Pennsylvania between 1912 and 1920.
 It includes the remaining extant mine resources and the archaeological remains of the mine.
 They consist of workers' housing, a variety of commercial and social buildings, and a modern draft entry mine with accompanying extractive buildings and structures.
 Notable buildings include the motor barn, supply house, electric substation, and Loyal Hanna Coal and Coke Company Office (1914).
 The mine operated until 1958.
Kemess Creek Airport, (TC LID: CBQ7) , is located near Kemess Mine, British Columbia, Canada.
Jualin Mine is a defunct gold mine located within the City and Borough of Juneau, Alaska approximately 44 mi northwest of downtown Juneau, Alaska.
 The Jualin gold deposit was discovered by prospector Frank Cook in 1895 and was initially mined by the Jualin Mining Company.
 A stamping mill with a daily capacity of 30 st of ore was installed early in the mine's operation.
 The mine operated intermittently from 1896 to 1901 and again from 1905 to 1908, when it was closed at a depth of 210 feet due to water infiltration and power shortages.
 In 1912, the mine was purchased by a Belgian group, which began investing in better equipment and deeper drilling.
 In 1914, the shaft was deepened to 325 feet, and mining took place at the 310-foot level.
 A drainage and haulage tunnel was planned to extend 7800 ft south of the mine to allow easy access to the mining levels, but the outbreak of World War I halted this effort when the extension was only 5000 ft long.
The Kemess Mine was an open-pit copper and gold mine, located just northeast of the foot of Thutade Lake, at the head of the Finlay River, in the Omineca Mountains of the Northern Interior of British Columbia, Canada.
 It was operated by Royal Oak Mines from 1998 to 1999, when it was bought by Northgate Minerals.
 Northgate operated the mine until its closure in 2011; that year Northgate was taken over by AuRico Gold.
 In 2014 AuRico Gold partitioned off its portion of kemess Mine ownership creating a new company called AuRico Metals.
 AuRico Metals is actively implementing permits for a block caving mine.
The Colomac Mine was a privately owned and operated open pit gold mine located 220 km northwest of Yellowknife in the Northwest Territories in Canada .
 The Colomac mine operated between 1990–1992, and 1994–1997.
 It was operated by Neptune Resources Limited that had little success in making a profit during its operation.
 In 1994, the mine had reopened under Royal Oak Mines Inc.
 Both Neptune Resources and Royal Oak Mines where both owned and operated by Peggy Witte.
 Due to low gold prices and high cost of mining, Royal Oak Mines was forced into bankruptcy.
 The Federal Government of Canada became owners of the mine, along with the related environmental issues.
 A major cleanup effort is under way to prevent the mine from polluting the environment, but this might be too late at this stage.
 This mine is now owned and controlled by the Indigenous and Northern Affairs department of the Federal government, while Public Works and Government services is the current contracting authority.
Sustut Peak, 2481 m (8140 ft), prominence: 1231 m, is the highest summit in the drainage of the Sustut River in British Columbia, Canada.
 Located in the Hogem Ranges west of Sustut Lake, which is at the Sustut River's headwaters, it is 8 km southwest of the road to the Kemess Mine
The Pyne Mine was a vertical shaft iron ore mine operated by the Woodward Iron Company and located near the community outside Bessemer, Alabama in Shades Valley.
 It was, along with Woodward's Songo Mine, one of only two shaft mines dug in the Birmingham District, and the last ore mine to operate in the region, closing in 1971.
Thutade Lake is located in the Omineca Mountains of the Northern Interior of British Columbia, Canada.
 About 40 km in length, and no more than about 2 km wide, the lake is primarily significant as the ultimate source of the Mackenzie River.
 The lake is at the head of the Finlay River, which joins the Peace River via Williston Lake.
 The area is very remote, being located about 260 km north of Smithers, although several mining operations for ores containing copper, lead, zinc and silver have occurred around the lake.
 The largest of these is the Kemess Mine, an iron and copper property originally owned by Royal Oak Mines and now by Northgate Minerals, located in the valley of Kemess Creek, which is off the northeast end of Thutade Lake.
 The mine is accessed by the Omineca Resource Road and other resource routes, and is 400 km by road from Prince George.
 Just downstream from the outlet of Thutade Lake, the Finlay plunges over 180 ft Cascadero Falls, and then through a series of cataracts in a twisting course until it begins its main northeastward trend.
 Cascadero Falls is slated for hydroelectric development in connection with the power needs of the area's mines.

Question: Were both Thompson-Lundmark Mine and Kemess Mine operated in the 1940's?
Answer: no