Geology of Ontario hiking trails takes you back in time.

Test Post Terrace, BC

TERRACE, BC

270 mya Metamorphic rocks, green volcanics
-volcanic island arc similar to Japan or Aleutians, with limestone reefs forming in shallow waters surround these islands
-Old Remo Rd. grey limestone exposures contains brachiopods, coral, crinoids, fusilinids

200 mya second mass of volcanoes built on top of first one, now brick red to purple rocks
-Kitsumkalum Mountain

180 mya: Island Arc collide with western edge of N.A. as Atlantic Ocean opened and plate tectonics moved NA westward
-lavas, limestone welded to edge of NA, creating mountains as units get deformed, folded and faulted

90-170 mya: Sedimentary rocks, some w/fossils, grey layered sandstone, mudstone
-mountains eroded, seds deposited into shallow sea that covered Terrace & Smithers to Dease Lake & Spatsizi Plateau Park
-rivers flow from east depositing sand
-backwater areas had accumulation of mud and dead vegetation (peat) which eventually gave coal deposits, natural gas
-dinosaurs roamed these coastal swamps and today can find fossil footprints plus other fossils
-Hazleton sandstone & shale

145 mya: Oeanic basaltic plateau Wrangellia collides with NA during late Jurassic early Cretaceous
-folding and faulting caused Coat Mountains to rise
-subduction zone formed with ocean crust sliding under Coast Mountains, causing rocks to melt tens of km below surface
-magma crystallized to form granitic rocks which today make up the Coast Mountains
-Copper Mountain granitic cliff face

50 mya: Mountain building compressive forces relax and much of BC starts to pull apart
-faulting created fault bounded valleys such as Kitsumkalum-Kitimat, flanked by Coast Mt on west & Hazelton Mt on east
-faults still traced today, act as conduits for hot waters circulating deep below the valley floor, rising to surface at Mt. Layton

2 mya: Ice sheets covered NA, reaching maximum 25,000 years when ice was 2 km thick over Terrace area
-ice deepened valleys, as glaciers flowed down to the ocean
-when glaciers retreated, meltwater beneath the ice laid down think plains of sand and gravel
-ice trapped under debris eventually melted and formed round kettle lakes south of Lakelse Lake
-Skeena and Kitsumkalum rivers cut down through the glacial deposits
-benches or flat terraces represent abandoned, older river plains now positioned above todays river
-Skeena River cuts through some the terraces at the “Horseshoe” on the north side of Terrace

250 years ago: Nass Valley lava flow
-20 km long exposure of bare rock and rubble extending from the Tseax volcanic cinder cone, some 100 m high
-lava flow permanently blocked flow of Tseax River, flood the valley and created a lava lake, killing some 2000 Nisg’a’ people
-the rocks occur as pumice

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