Show k i w President Talmage's Lecture The public l lecture course was br brought ugh to tol to a a Cv very V ry su successful close close by President President- Talmage in his rr I 1 r. r Earths Earth s F Fire Fire- H a a a- study of volcanoes F Following is a a short synopsis of the address I The popular i id idea fe of ea o of a volcano is is I that it is is' is ess es's essentially nt a a a amount mount mountain n while hile in reality it is the very very opposite viz a aho ahole ahole ho hole e in the ground T The e mound orn or n mountain nta n is is is a result not a cause noran noran nor noran an an e essential H feature The n name me i is a a changed form o of of V ario d' d a d designation designation sig nat nation given given to toa to a a Small and arid corrip comparatively comparatively ra- ra in insignificant fire h hole fire le in the Mediterranean Active volcanoes pr present sent two extreme extreme types types l 1 a quiet or igneous fusion type well represented b by bythe bythe the Hawaiian volcanoes 2 the ex explosive explosive ex- ex plosive type of which the J Javanese ava se volca volcanoes oes particularly is re re- tive The Mediterranean volcanoes vol vol- f c canoes partake canoes noes partake of the nature of both types eruption Inthe In the eruption n of the fir first t type type true lava i. i e e. e molten rock is ejected i while 4 i in in the the 1 oth other r div finely divided r rock kl i rn material is thrown out in in inthe the form of volcanic dust or or ashes lap Il or or c cinders and sometimes large mass masses s of rock The presumed cause cause of vol volcanic anic anic action actio iS isn is J internal heat Many t theories orie h-a h have have been advanced in explanation The internal in internal in inq q I t nal fluidity idea is now g generally aB abandoned the heat Beat b being ing regarded as o of l local c f occurrence fence n e. e Chen Chemical ical ac action n may have much to do with igneous phenomena and heat ge generated by hy the mechanical motion of c crust crust blocks blocks blocks' is p perhaps the cause Physicists Physicists' and geologists now agree that a much lower degree of heat than was once supposed may account account- for this action A temperature temperature temperature tem tem- of degrees Fahrenheit if water be present and particularly if the water be alkaline will under pressure produce semi cemi and even perfect fusion of rocks The distribution of volcanoes indicates that the proximity to water is necessary to violent action Active vol vol- 1 J I r canoes occur near the sea shore and in recent strata they are arranged in lines lines lines' and groups suggesting that they are in some some way associated with earth fissures of very gr great at extent Many igneous p phenomena rna may be properly regarded as s secondary volcanic occurrences occurrences e. e e. e g. g t hot springs geysers geysers etc j i jand and in one sense sense sens volcanic craters belong to the order of f secondary phenomena In earlier stages of the earths earth's history history- when vu was more intense eruption eruption eruption tion took place I through fissures other than craters I Y L After ft r th thus s outlining the subject the speaker called the stereopticon to o his aid and ard pre presented a series of over 50 excellent views exhibiting volcanic ph phenomena in most of their phases The photographs were extremely real real- A comparison w was was' s dra drawn wn between between J the v volcanic nic ac activity on op the earth and the same o order der of activity vi ty on o other her planets The sun and aid the moon were r referred to as extremes extremes s of f such action the sun sup being in its earlier a and d more intense stage of fiery existence and the r moon while exhibiting n numerous s 0 old 4 craters being really cold and dead dead 1 t an 4 l J 1 t J J 4 1 |