按键盘上方向键 ← 或 → 可快速上下翻页，按键盘上的 Enter 键可回到本书目录页，按键盘上方向键 ↑ 可回到本页顶部！
————未阅读完？加入书签已便下次继续阅读！
but touch the floor。 lyell’s only real job in life was asprofessor of geology at king’s college in london from 1831 to 1833。 it was around this timethat he produced the principles of geology； published in three volumes between 1830 and1833； which in many ways consolidated and elaborated upon the thoughts first voiced byhutton a generation earlier。 （although lyell never read hutton in the original； he was a keenstudent of playfair’s reworked version。）between hutton’s day and lyell’s there arose a new geological controversy； which largelysuperseded； but is often confused with； the old neptunian–plutonian dispute。 the new battlebecame an argument between catastrophism and uniformitarianism—unattractive terms for animportant and very long…running dispute。 catastrophists； as you might expect from the name；believed that the earth was shaped by abrupt cataclysmic events—floods principally； which iswhy catastrophism and neptunism are often wrongly bundled together。 catastrophism wasparticularly forting to clerics like buckland because it allowed them to incorporate thebiblical flood of noah into serious scientific discussions。 uniformitarians by contrast believedthat changes on earth were gradual and that nearly all earth processes happened slowly； overimmense spans of time。 hutton was much more the father of the notion than lyell； but it waslyell most people read； and so he became in most people’s minds； then and now； the father ofmodern geological thought。
lyell believed that the earth’s shifts were uniform and steady—that everything that hadever happened in the past could be explained by events still going on today。 lyell and hisadherents didn’t just disdain catastrophism； they detested it。 catastrophists believed thatextinctions were part of a series in which animals were repeatedly wiped out and replacedwith new sets—a belief that the naturalist t。 h。 huxley mockingly likened to “a succession ofrubbers of whist； at the end of which the players upset the table and called for a new pack。” itwas too convenient a way to explain the unknown。 “never was there a dogma more calculatedto foster indolence； and to blunt the keen edge of curiosity；” sniffed lyell。
lyell’s oversights were not inconsiderable。 he failed to explain convincingly howmountain ranges were formed and overlooked glaciers as an agent of change。 he refused toaccept louis agassiz’s idea of ice ages—“the refrigeration of the globe；” as he dismissivelytermed it—and was confident that mammals “would be found in the oldest fossiliferousbeds。” he rejected the notion that animals and plants suffered sudden annihilations； andbelieved that all the principal animal groups—mammals； reptiles； fish； and so on—hadcoexisted since the dawn of time。 on all of these he would ultimately be proved wrong。
yet it would be nearly impossible to overstate lyell’s influence。 the principles of geologywent through twelve editions in lyell’s lifetime and contained notions that shaped geological thinking far into the twentieth century。 darwin took a first edition with him on thebeaglevoyage and wrote afterward that “the great merit of the principles was that it altered thewhole tone of one’s mind； and therefore that； when seeing a thing never seen by lyell； one yetsaw it partially through his eyes。” in short； he thought him nearly a god； as did many of hisgeneration。 it is a testament to the strength of lyell’s sway that in the 1980s when geologistshad to abandon just a part of it to acmodate the impact theory of extinctions； it nearlykilled them。 but that is another chapter。
meanwhile； geology had a great deal of sorting out to do； and not all of it went smoothly。
from the outset geologists tried to categorize rocks by the periods in which they were laiddown； but there were often bitter disagreements about where to put the dividing lines—nonemore so than a long…running debate that became known as the great devonian controversy。
the issue arose when the reverend adam sedgwick of cambridge claimed for the cambrianperiod a layer of rock that roderick murchison believed belonged rightly to the silurian。 thedispute raged for years and grew extremely heated。 “de la beche is a dirty dog；” murchisonwrote to a friend in a typical outburst。
some sense of the strength of feeling can be gained by glancing through the chapter titlesof martin j。 s。 rudwick’s excellent and somber account of the issue； the great devoniancontroversy。 these begin innocuously enough with headings such as “arenas of gentlemanlydebate” and “unraveling the greywacke；” but then proceed on to “the greywacke defendedand attacked；” “reproofs and recriminations；” “the spread of ugly rumors；” “weaverrecants his heresy；” “putting a provincial in his place；” and （in case there was any doubtthat this was war） “murchison opens the rhineland campaign。” the fight was finally settledin 1879 with the simple expedient of ing up with a new period； the ordovician； to beinserted between the two。
because the british were the most active in the early years； british names are predominantin the geological lexicon。 devonian is of course from the english county of devon。 cambrianes from the roman name for wales； while ordovician and silurian recall ancient welshtribes； the ordovices and silures。 but with the rise of geological prospecting elsewhere；names began to creep in from all over。jurassic refers to the jura mountains on the border offrance and switzerland。permian recalls the former russian province of perm in the uralmountains。 forcretaceous （from the latin for “chalk”） we are indebted to a belgian geologistwith the perky name of j。 j。 d’omalius d’halloy。
originally； geological history was divided into four spans of time： primary； secondary；tertiary； and quaternary。 the system was too neat to last； and soon geologists werecontributing additional divisions while eliminating others。 primary and secondary fell out ofuse altogether； while quaternary was discarded by some but kept by others。 today onlytertiary remains as a mon designation everywhere； even though it no longer represents athird period of anything。
lyell； in his principles； introduced additional units known as epochs or series to cover theperiod since the age of the dinosaurs； among them pleistocene （“most recent”）； pliocene（“more recent”）； miocene （“moderately recent”）； and the rather endearingly vague oligocene（“but a little recent”）。 lyell originally intended to employ “…synchronous” for his endings；giving us such crunchy designations as meiosynchronous and pleiosynchronous。 thereverend william whewell； an influential man； objected on etymological grounds andsuggested instead an “…eous” pattern； producing meioneous； pleioneous； and so on。 the “…cene” terminations were thus something of a promise。
nowadays； and speaking very generally； geological time is divided first into four greatchunks known as eras： precambrian； paleozoic （from the greek meaning “old life”）；mesozoic （“middle life”）； and cenozoic （“recent life”）。 these four eras are further dividedinto anywhere from a dozen to twenty subgroups； usually called periods though sometimesknown as systems。 most of these are also reasona