Guatemala's Volcanic Eruption

The eruption of a volcano inwards Republic of Guatemala as well as its tragic consequences accept drawn attending across the globe this week.  Some volition blame the lawsuit on the random violence of nature piece others volition come across the manus of God inwards the devastation as well as suffering.  But if y'all must bill mortal or something, blame the Atlantic Ocean.

During the Permian Period, simply about 250 1000000 years agone (MYA), the Continents had merged to degree Pangea.  By the Triassic, nearly 200 MYA, the Tethys Sea opened, separating Laurasia (the northern Continents) from Gondwanaland (the southern Continents).  Then, during the Jurassic Period (some 150 MYA), the Atlantic began to opened upward as well as the American Continents were pushed westward, a procedure that continues today.  In concert, the oceanic Farallon Plate was forced to subduct beneath the advancing Continental Plates; today, the Juan de Fuca Plate (in the Pacific Northwest), the Cocos Plate (west of United Mexican United States of America as well as Central America) as well as the Nazca Plate (west of South America) are the main remnants of the Farallon Plate as well as all decease along to subduct beneath the American Plates.

As these oceanic plates subduct, their leading border melts when it approaches the Earth's mantle, triggering the formation of volcanoes (the Cascades, the western mountains of United Mexican United States of America as well as Central America, as well as the Andes); earthquakes as well as tsunamis equally good outcome from this tectonic activity.  The electrical current eruption inwards Guatemala, releasing volcanic ash, pyroclastic flows as well as lahars, is thence a secondary effect of the Atlantic's expansion.  populace did non halt evolving when nosotros humans appeared!

Northwest To Ketchikan

Escaping the latest oestrus moving ridge along the Colorado Front Range, my married adult woman in addition to I volition endure visiting friends inwards Ketchikan, Alaska, over the adjacent several days.  There nosotros volition taste afternoon highs inwards the 60s (F) in addition to overnight lows inwards the 50s; of course, pelting showers are equally good inwards the forecast, equally i mightiness await inwards Southeast Alaska.

As I discussed in Alaska's Collage of Terranes, nearly of the State is a mosaic of exotic terranes in addition to volcanic isle arcs, subsequently molded yesteryear glaciers, earthquakes, volcanic eruptions, torrents of meltwater in addition to fluctuating body of body of water levels.  Ketchikan sits inwards the Gravina Belt, composed of mid Jurassic to early on Cenozoic volcanic rocks, sandwiched betwixt the Alexander Terrane, to the west, in addition to the Stikine Terrane, to the east.  The Alexander Terrane is particularly interesting; its Silurian in addition to Devonian strata in addition to their cargo of fossils signal that it was torn away from Siberia equally the Northern Pacific opened.  The Stikine Terrane, on the other hand, formed equally a volcanic isle arc from the belatedly Paleozoic Era into the early on Mesozoic.

Today, Ketchikan, sitting on the Inside Passage, is a cruise send port during the summertime months.  Having express fourth dimension for our journey, nosotros volition endure flight from Denver (with a plane alter inwards Seattle).  More on our endangerment inwards upcoming posts.

Above The Cascades & Corking Basin

Flying dorsum to Denver, yesterday, nosotros changed planes inwards Seattle.  On that 2d flight, nosotros took off to the south, before long passing the massive mass of Mt. Ranier, to our east.  Curving southeastward, nosotros together with therefore caught sight of the remnant cone of Mt. St. Helens to our southwest and, inside a few minutes, flew over the snowy crest of Mt. Adams.  Next came the distinctive split of Mt. Hood, across the Columbia River Valley, together with other prominent summits further south; unfortunately, haze obscured the distant horizon together with I was unable to locate Mt. Shasta, inwards Northern California.

Having formed over the yesteryear 36 1 one m thousand years, equally the Farallon together with its remnant Juan de Fuca Plate convey been subducting beneath the North American Plate, the Cascades stretch from west-central Washington to Northern California together with leave of absence on to split today.  Indeed, many Cascade volcanoes convey developed together with eroded (or exploded) away during that fourth dimension together with the prominent volcanic peaks mentioned higher upwardly are less than two 1 one m thousand years old; the eruption of Mt. St. Helens, inwards 1980, was a clear indication that the attain is withal evolving.

East of the Cascades, is the high, dry out desert of the Great Basin, stretching from eastern Oregon together with California across Nevada, southernmost Idaho together with western Utah.  Fault-block ranges, running due north to south, are separated yesteryear wide valleys which harbor sage grasslands, seasonal rivers, sinks, ephemeral lakes together with a few large saline lakes. Unfortunately, clouds obscured the mountains of Utah together with Colorado until nosotros crossed the Front Range higher upwardly Rocky Mountain National Park together with descended into Metro Denver.

Geologic History Of Scotland

In the slow Precambrian Era in addition to into the Cambrian Period, the basement stone of Scotland was purpose of proto-North America, having accreted to that Continent equally a serial of exotic terranes.  The Iapetus Ocean separated this continental volume from that of England in addition to Western Europe.

Then, virtually 450 1 one 1000 thousand years agone (MYA), the Iapetus Ocean unopen in addition to the 2 continents collided, triggering the Caledonian Orogeny; much later, virtually 150 MYA, the Atlantic Ocean opened in addition to Scotland remained amongst Europe.  Today, ancient rocks that preceded the Caledonian Orogeny underlie most of Scotland simply surface primarily across the Western Islands in addition to the Highlands; the latter share is divided into the Northwest Highlands in addition to the Grampian Mountains past times the Great Glen Fault.  As these Highlands crumpled upward, volcanism, erosion in addition to displacement of emplaced metamorphic crust produced the complicated geology of that region.  South of the Highlands Boundary Fault, the Central Lowlands stand upwards for a Rift Valley, characterized past times Paleozoic sediments, volcanic intrusions in addition to to a greater extent than recent glacial deposits.  Finally, the Southern Uplands, bordering England, are comprised of uplifted in addition to eroded Silurian crust from the Iapetus Ocean.

Acting on this underlying mosaic of Precambrian in addition to Paleozoic bedrock, the Pleistocene Glaciers (1.8 1 one 1000 thousand to 10 one 1000 years ago) plowed downward the higher peaks, gouged out canyons in addition to valleys in addition to and hence left behind layers of till equally they receded northward.  In addition, their meltwaters scoured the terrain in addition to rising seas drowned the coastline, separating the western in addition to northern islands from the Scottish mainland.