,devils ,postpile ,,national ,,monument ,,california ,,devils ,,postpile ,,national ,,monument ,along the picturesque ,middle ,fork of the ,san ,joaquin ,river at #b1cjj meters 7#g1fjj feet7 on the western slopes of the ,sierra ,nevada lies ,devils ,postpile ,national ,monument4 ,the #cbd-;hectare 7#hjj-;acre7 monument near the resort community of ,mammoth ,lakes includes one dominant feature3 a formation of columnar basalt known as ,devils ,postpile4 ,another important feature in the area is ,rainbow ,falls4 ,pumice is the dominant rock-type encountered1 but basalt1 andesite1 rhyodacite1 and granite lie just under the surface and crop out in many places4 ,plants and animals are typical of lodgepole pine and red fir forests4 ,to see the features of the monument one must walk4 ,,devils ,,postpile ,the formation of ,devils ,postpile began when basalt lava erupted in the valley of the ,middle ,fork of the ,san ,joaquin ,river4 ,as lava flowed from the vent1 it filled the valley near the ,postpile to a depth of #abb meters 7#djj feet74 ,recent radiometric dating of rocks thought to correlate with basalt of ,devils ,postpile suggest an age of less than #ajj1jjj years4 ,surface cracks formed when tensions caused by the shrinkage of the cooling lava were greater than the strength of the lava itself4 ,each crack branched when obtaining a critical length and together with other cracks formed a pattern on the surfaces of the flow4 ,ideal conditions allowed surface cracks to deepen1 resulting in the formation of long columns4 ,illustration3 uncaptioned ,approximately #aj1jjj years ago1 glaciers flowed down the ,middle ,fork of the ,san ,joaquin ,river4 ,this moving ice easily overrode the fractured mass of lava and quarried away one side of the ,postpile1 exposing a sheer wall of columns #ah meters 7#fj feet7 high4 ,many fallen columns now lie fragmented on the talus slope below4 ,a hike to the top of the ,postpile reveals not only a cross section of the posts1 but the most interesting effect of the ice--polished tops of the basalt columns4 ,here1 the column ends are exposed like a tiled floor and exhibit parallel striations where the glacier dragged rocks across them4 ,even though ,devils ,postpile is among the world's finest examples of columnar-jointed basalt1 it is not unique4 ,giant's ,causeway in ,ireland and ,fingal's ,cave in ,scotland are similar formations4 ,,soda ,,springs ,nearby mineral springs are evidence of recent local volcanic activity4 ,the ,soda ,springs lie on a gravel bar in the ,san ,joaquin ,river just north of the ,postpile4 ,here1 gases driven upward from hot areas deep in the earth combine with ground water to produce cold and highly carbonated mineralized springs4 ,the iron present in ,soda ,springs water oxidizes on exposure to the atmosphere and stains river gravel a reddish brown4 ,illustration3 uncaptioned ,,safety ,for your safety1 remember that there are hazards in the mountains that usually do not exist in the city4 ,stay on designated trails2 these are the safest places to hike4 ,use caution when viewing features from near cliff or gorge edges4 ,footing can be hazardous4 ,,warning3 ,bears inhabit the monument4 ,proper food storage is required by ,federal law4 ,illustration3 uncaptioned ,,monument ,,boundary ,,campground ,,to ,u4,s4 #cif ,,mammoth ,,lakes ,,ranger ,,station 7,el4 #g1efj ft47 ,,sotcher ,,lake ,soda ,springs ,,devils ,,postpile ,king ,creek ,trail ,san ,joaquin ,river ,,reds ,,meadow ,,the ,,buttresses ,middle ,fork ,john ,muir ,trail ,boundary ,creek ,,rainbow ,,falls 7#aja feet7 ,,lower ,,falls ,illustration3 uncaptioned ,,rainbow ,,falls ,at ,rainbow ,falls the ,middle ,fork of the ,san ,joaquin ,river drops #ca meters 7#aja feet7 over an andesite and rhyodacite cliff4 ,it is thought that after the last glacier melted1 the river flowed downstream from ,devils ,postpile in channels about #deg meters 7#a1ejj feet7 west of its present course4 ,flowing in these older channels1 it cut through the rhyodacite lava down to granite1 leaving a cliff of rhyodacite for its eastern bank4 ,then1 some distance upstream1 the waters were diverted eastward4 ,the river left its bed to follow its present path until it returned to the old channel1 by cascading down the cliff it had earlier cut4 ,thus ,rainbow ,falls was formed4 ,a stairway and short trail lead to the bottom of the falls1 where numerous flowers and grasses form an enchanting garden4 ,cars may be driven to within #a4f kilometers 7#a mile7 of the falls via the road to ,reds ,meadow4 ,,about ,,your ,,visit ,the monument is reached by a #af-kilometer 7#aj-mile7 drive west from ,u4,s4 #cie on ,s4,r4 #bjc to ,minaret ,summit1 then by #aa4b kilometers 7#g miles7 of paved narrow mountain road4 ,the monument is administered by the ,national ,park ,service1 ,u4,s4 ,department of the ,interior4 ,for more information write3 ,superintendent1 ,sequoia and ,kings ,canyon ,national ,parks1 ,three ,rivers1 ,,ca #icbga4 ,park rangers are on duty to assist you1 to conduct interpretive activities1 and to enforce the regulations4 ,closed in winter4 ,accommodations and services4 ,meals1 lodging1 groceries1 gasoline1 horses1 and other facilities and services are available at ,mammoth ,lakes or nearby ,reds ,meadow4 ,camping4 ,a campground is maintained near the ranger station from about ,july #a to ,october #ae1 depending on the weather4 ,hiking4 ,trips may be made north or south on the ,john ,muir ,trail and west on the ,king ,creek ,trail4 ,the monument also has several short trails4 ,fishing and hunting4 ,fishing is permitted in the monument1 but hunting is prohibited4 ,a ,california angling license with appropriate stamps is required for persons #af years of age or over4 ,pets4 ,pets are permitted in the monument only if they are kept under direct physical control at all times4 ,national ,park ,service ,u4,s4 ,,department ,,of ,,the ,,interior ,,gpo #aihd--dba-fac_/cag ,reprint #aihd ,transcriber's ,notes --,silently corrected a few typos4 --,retained publication information from the printed edition3 this e,book is public-domain in the country of publication4 --,in the text versions only1 text in italics is delimited by underscores4