觀(guan)(guan)音(yin)(yin)山(Kuan-yin Mountain),舊(jiu)稱新(xin)宜(yi)山,別(bie)名八里坌山(淡水(shui)廳志載)。位于臺灣省新(xin)北市五股區(qu)(qu)、八里區(qu)(qu)交界(jie),海拔標高616米,由淡水(shui)河北岸向南遙望,全區(qu)(qu)有十八連峰,區(qu)(qu)內有多座古剎,更增添觀(guan)(guan)音(yin)(yin)山的靈性,其中有數(shu)間供奉觀(guan)(guan)世(shi)音(yin)(yin)菩(pu)薩的觀(guan)(guan)音(yin)(yin)寺。
觀(guan)音(yin)山,亦(yi)有不少納(na)骨塔及墓園錯落其間,該山西臨臺灣(wan)海(hai)峽,東(dong)北隔淡水河遠望關(guan)渡,昔日(ri)的(de)“坌嶺吐霧”為淡水八(ba)大景(jing)之一,山頂又稱“硬(ying)漢嶺”,全山屬北海(hai)岸及觀(guan)音(yin)山風景(jing)區(qu)。
觀(guan)(guan)音(yin)山(shan)(shan)(shan)自古(gu)便(bian)有(you)登(deng)山(shan)(shan)(shan)活動,目(mu)前八里登(deng)觀(guan)(guan)音(yin)山(shan)(shan)(shan)的路線(xian)(xian)共有(you)四條主(zhu)要路線(xian)(xian),其中以乘車至觀(guan)(guan)音(yin)山(shan)(shan)(shan)風(feng)景區管理處(chu),由凌云禪寺旁鐵漢步(bu)道(dao)經硬(ying)(ying)漢嶺(ling)拾階而上登(deng)頂為最熱(re)門路線(xian)(xian)。硬(ying)(ying)漢嶺(ling)為1961年憲兵(bing)學校(xiao)300名學員開(kai)辟了一條直達山(shan)(shan)(shan)頂的登(deng)山(shan)(shan)(shan)步(bu)道(dao),為鼓勵(li)學員學硬(ying)(ying)漢而來作(zuo)硬(ying)(ying)漢而去,而名硬(ying)(ying)漢嶺(ling)。
硬漢嶺為火山碎屑巖與凝灰(hui)角礫巖所(suo)構成,1992,1993年來時有(you)豪雨(yu)山崩土石滑動,步道毀壞并危(wei)及凌云禪(chan)寺安(an)全。寄望能(neng)有(you)效妥(tuo)當的維護整修以保持靈山古剎之原(yuan)有(you)古樸韻(yun)味。
由于季風吹來臺(tai)灣(wan)海峽的水汽,遇到觀音山嶺的阻擋(dang),便(bian)降下化為云霧,有如(ru)飄綿(mian)滾絮、變幻(huan)無常,蔚為奇觀.被文(wen)人雅士命名(ming)為“坌嶺吐霧”,名(ming)列清代淡(dan)北(bei)八景之一(yi)。同治年間大龍峒舉人陳(chen)維英曾(ceng)題詩贊曰:“坌嶺微(wei)茫八里間,連朝吐霧罩鴉鬟,此中定有深藏貌,未許(xu)分明見一(yi)斑(ban)”。
觀音山(shan)在淡水(shui)(shui)河(he)(he)(he)河(he)(he)(he)口(kou)南(nan)畔,東與大屯山(shan)群(qun)峰隔河(he)(he)(he)相峙,西南(nan)毗接林(lin)口(kou)臺地。形似(si)仰臥之觀音,山(shan)頂(ding)空曠怡人,立足其(qi)上可俯瞰河(he)(he)(he)口(kou)及淡水(shui)(shui)鎮、臺北(bei)市郊景(jing)色,為淡水(shui)(shui)八景(jing)之一。凌云古剎坐落(luo)山(shan)腰,后(hou)另建新(xin)廟于古剎后(hou)方約(yue)數百公尺處(即觀音山(shan)腹(fu)),名曰凌云禪寺,是(shi)游人休憩(qi)處。
觀(guan)音山(shan)(shan)(shan)(shan)(shan)為一錐狀(zhuang)火(huo)山(shan)(shan)(shan)(shan)(shan),是大屯火(huo)山(shan)(shan)(shan)(shan)(shan)匯最西的一部分,其(qi)北側(ce)(ce)以(yi)火(huo)山(shan)(shan)(shan)(shan)(shan)熔巖(yan)(yan)為主,南側(ce)(ce)以(yi)火(huo)山(shan)(shan)(shan)(shan)(shan)碎(sui)屑(xie)流為主,火(huo)成(cheng)(cheng)巖(yan)(yan)以(yi)安山(shan)(shan)(shan)(shan)(shan)巖(yan)(yan)為主,另外含有一些早(zao)期噴發的玄武巖(yan)(yan),越晚期的噴發則形(xing)成(cheng)(cheng)含角閃石的安山(shan)(shan)(shan)(shan)(shan)巖(yan)(yan)。淡(dan)水(shui)河沿著觀(guan)音山(shan)(shan)(shan)(shan)(shan)麓流入臺灣(wan)海(hai)峽(xia),因兩側(ce)(ce)的火(huo)山(shan)(shan)(shan)(shan)(shan)熔巖(yan)(yan)與碎(sui)屑(xie)物漫流入海(hai),而形(xing)成(cheng)(cheng)火(huo)山(shan)(shan)(shan)(shan)(shan)海(hai)岸。
山(shan)上坐(zuo)落著(zhu)不少名剎古寺,并可溯(su)溪(xi)觀(guan)瀑、觀(guan)鷹(ying)賞鳥、眺望(wang)半個臺(tai)北(bei)和壯(zhuang)麗的(de)大(da)屯山(shan)列,是一處豐富的(de)自然觀(guan)賞去處。觀(guan)音山(shan)上的(de)山(shan)徑溪(xi)谷(gu)四通八達,登山(shan)路線(xian)林(lin)林(lin)總總、難易不同(tong),登山(shan)客(ke)可以揀挑適(shi)合自己體力的(de)山(shan)徑上山(shan)。其中最(zui)大(da)眾化的(de)路線(xian)是從五(wu)股(gu)的(de)觀(guan)音山(shan)站牌出(chu)發,沿(yan)山(shan)階上登凌(ling)云禪寺,再由寺后的(de)牌樓往上走(zou),約(yue)1小時可抵硬漢嶺(ling)。在(zai)(zai)此(ci)登高眺覽,視野遼(liao)闊,整個臺(tai)北(bei)市(shi)自新光大(da)樓以北(bei)的(de)市(shi)景都在(zai)(zai)眼下,而對面的(de)大(da)屯山(shan)列及淡水河口山(shan)海(hai)相映的(de)景象更是壯(zhuang)觀(guan)。
白天上觀(guan)音山,可隔著門墻老樹感受楞(leng)嚴閣、開山院的古樸莊(zhuang)嚴,遠眺淡水八景之一的“坌(ben)領(ling)吐霧”;傍晚時分坐觀(guan)落日(ri)晚霞,淡水暮色最令人心動;或于夜(ye)(ye)幕低垂時看淡水河畔夜(ye)(ye)景,萬(wan)家燈火(huo)閃爍明滅,另(ling)有(you)一番擾攘人間之美。
在荷(he)蘭人統治(zhi)時代(dai),觀音山(shan)叫(jiao)淡水山(shan)(出現在1654年荷(he)蘭人‘淡水與其附(fu)近村(cun)社暨(ji)雞籠島略圖’中編號37的(de)Tamswijse berch),但漢人習稱八(ba)里分(坌(ben))山(shan),系(xi)因山(shan)邊的(de)原住民部(bu)落八(ba)里坌(ben)社而得名。
康熙年間(jian),乃(nai)延(yan)用八(ba)里(li)坌山的(de)(de)地(di)名(ming)(康熙二(er)(er)十四年蔣毓英“臺灣(wan)府志(zhi)”)。清朝雍正年間(jian)(西元(yuan)1710年代)也曾(ceng)改為“興直山”,但在各地(di)方史籍(ji)中仍以(yi)“八(ba)里(li)坌山”稱之。后(hou)來(lai)改為觀音山的(de)(de)說法有(you)二(er)(er):一(yi)說是(shi)乾(qian)隆17年(西元(yuan)1752年)客家籍(ji)貢生(sheng)胡焯猷(福建(jian)(jian)汀州(zhou)永定人)在山路西云巖籌建(jian)(jian)大士觀(今五(wu)股區西云巖寺)而(er)得名(ming),一(yi)說是(shi)由于山棱起伏(fu)變化(hua),從關渡一(yi)帶眺(tiao)望時,山型起伏(fu)貌(mao)似觀音菩薩(sa)的(de)(de)面容(rong)仰(yang)天的(de)(de)側面而(er)得名(ming)。
據臺灣著名(ming)(ming)的地(di)(di)(di)名(ming)(ming)學者-陳國(guo)章教授所著的臺灣地(di)(di)(di)名(ming)(ming)詞典,認為該地(di)(di)(di)的地(di)(di)(di)名(ming)(ming)是(shi)因“形似觀音菩薩的山”而得(de)名(ming)(ming)。
1937年12月27日(ri),日(ri)本(ben)殖民(min)當(dang)局以(yi)臺灣寶島山水風光(guang)秀麗籌劃成(cheng)立大屯(tun)觀音山、次高(gao)山太(tai)魯閣和新高(gao)阿里山三(san)座公園,并于1941年3月10日(ri)發行紀(ji)念郵票、小全張(zhang)及臺灣公園寫真集,可惜因戰爭而(er)延(yan)宕。
二次(ci)世界大戰結束后,臺灣回歸(gui)中國,觀(guan)(guan)音山(shan)(shan)優(you)良的屏障、視(shi)野的寬(kuan)闊好山(shan)(shan)好水,為(wei)(wei)國人所認(ren)為(wei)(wei)風水寶(bao)地,濫挖濫葬,一(yi)片零亂有礙視(shi)野觀(guan)(guan)瞻(zhan)。相較之(zhi)下,景觀(guan)(guan)資源大不(bu)如往昔,已失去(qu)了成為(wei)(wei)公(gong)園之(zhi)基本(ben)要件(jian),十分可惜。
觀音山(shan)是臺(tai)灣北部(bu)火(huo)成巖區(qu)中(zhong)最西北側之(zhi)火(huo)山(shan)單(dan)元,以(yi)淡水河與大屯(tun)火(huo)山(shan)群(qun)遙(yao)遙(yao)相望(wang),基本上(shang)為單(dan)一(yi)中(zhong)心(xin)噴發的火(huo)山(shan)碎屑、凝(ning)灰巖與熔巖交替組成之(zhi)復(fu)式(shi)火(huo)山(shan)。觀音山(shan)火(huo)山(shan)之(zhi)主(zhu)(zhu)體(ti)可(ke)能是一(yi)中(zhong)央噴發之(zhi)錐(zhui)狀火(huo)山(shan),錐(zhui)體(ti)半(ban)徑約1~2公里(li),噴發中(zhong)心(xin)在觀音山(shan)主(zhu)(zhu)峰之(zhi)東南(nan)方。在凌(ling)云山(shan)一(yi)帶之(zhi)半(ban)環(huan)形(xing)之(zhi)連(lian)峰可(ke)能是火(huo)山(shan)口壁之(zhi)西側。
在此(ci)以(yi)東(dong)(dong),于石(shi)(shi)壁坑附(fu)近之(zhi)(zhi)地形(xing),呈馬蹄狀(zhuang)之(zhi)(zhi)半(ban)圓形(xing)凹陷可能(neng)是火山(shan)(shan)口(kou)所(suo)在,但火山(shan)(shan)口(kou)之(zhi)(zhi)東(dong)(dong)壁已經爆破或(huo)熔巖(yan)(yan)(yan)溢流(liu)巖(yan)(yan)(yan)漿(jiang)庫匱空(kong)塌陷而(er)崩塌,其部分碎屑構成分布于凌云山(shan)(shan)以(yi)東(dong)(dong)地區之(zhi)(zhi)集塊巖(yan)(yan)(yan)或(huo)原先之(zhi)(zhi)火山(shan)(shan)碎屑流(liu)與火山(shan)(shan)礫巖(yan)(yan)(yan)。觀(guan)音(yin)(yin)山(shan)(shan)火山(shan)(shan)活動(dong)時可能(neng)不猛(meng)烈,因而(er)出露之(zhi)(zhi)主(zhu)(zhu)體并未含(han)有可觀(guan)的(de)火山(shan)(shan)碎屑巖(yan)(yan)(yan),仍以(yi)厚(hou)層的(de)巖(yan)(yan)(yan)流(liu)為主(zhu)(zhu)。觀(guan)音(yin)(yin)山(shan)(shan)噴出熔巖(yan)(yan)(yan)流(liu)也和(he)(he)大(da)屯火山(shan)(shan)群相(xiang)似(si),均(jun)以(yi)安山(shan)(shan)巖(yan)(yan)(yan)為主(zhu)(zhu)。一般安山(shan)(shan)巖(yan)(yan)(yan)常呈灰(hui)(hui)或(huo)灰(hui)(hui)黑(hei)色,且(qie)多(duo)呈斑狀(zhuang)結(jie)構,由結(jie)晶(jing)(jing)較(jiao)粗大(da)之(zhi)(zhi)斑晶(jing)(jing)散布在石(shi)(shi)質細密(mi)之(zhi)(zhi)石(shi)(shi)基(ji)中。斑晶(jing)(jing)礦(kuang)物以(yi)鎂鐵(tie)(tie)礦(kuang)物為多(duo),包(bao)括橄欖石(shi)(shi)、輝石(shi)(shi)、紫蘇(su)輝石(shi)(shi)、角閃石(shi)(shi)、黑(hei)云母(mu)等礦(kuang)物,此(ci)外還(huan)有灰(hui)(hui)白色的(de)斜長(chang)石(shi)(shi)。石(shi)(shi)基(ji)以(yi)斜長(chang)石(shi)(shi)和(he)(he)一些鎂鐵(tie)(tie)礦(kuang)物的(de)微晶(jing)(jing)(肉(rou)眼不能(neng)分辨(bian)的(de))和(he)(he)無結(jie)晶(jing)(jing)的(de)火山(shan)(shan)玻璃所(suo)組成。
本區安山巖熔巖依噴(pen)發(fa)之先后,由下(xia)而上(shang)(shang)可(ke)分(fen)(fen)別為三層(ceng),各層(ceng)巖石在組織上(shang)(shang)和成分(fen)(fen)上(shang)(shang)都(dou)有多(duo)少不(bu)同。
底層(ceng)(ceng)(或(huo)第(di)一層(ceng)(ceng))是(shi)粗粒普通輝(hui)石(shi)(shi)玄武巖(yan)(yan)或(huo)玄武巖(yan)(yan)質安山(shan)巖(yan)(yan)熔巖(yan)(yan)。主要露(lu)出于(yu)火山(shan)錐體(ti)之(zhi)(zhi)(zhi)中(zhong)心地帶,包括(kuo)石(shi)(shi)壁(bi)坑及其東側(ce)之(zhi)(zhi)(zhi)米倉村、烏山(shan)頭,至福隆(long)山(shan)等地。安山(shan)巖(yan)(yan)顏色(se)深灰,呈斑(ban)(ban)狀(zhuang)結構(gou)有許多(duo)(duo)黑綠色(se)之(zhi)(zhi)(zhi)普通輝(hui)石(shi)(shi)斑(ban)(ban)晶(jing),散布在灰色(se)細(xi)晶(jing)之(zhi)(zhi)(zhi)石(shi)(shi)基中(zhong),斑(ban)(ban)晶(jing)大者可達5公(gong)里左右。在顯微鏡下觀察巖(yan)(yan)石(shi)(shi)薄片,這些斑(ban)(ban)晶(jing)多(duo)(duo)成(cheng)雙(shuang)晶(jing)或(huo)叢晶(jing)(由(you)數(shu)個晶(jing)體(ti)結集(ji)而(er)成(cheng)),輝(hui)石(shi)(shi)之(zhi)(zhi)(zhi)外還有多(duo)(duo)數(shu)斜長石(shi)(shi)和少(shao)數(shu)橄欖石(shi)(shi)。中(zhong)層(ceng)(ceng)(或(huo)第(di)二層(ceng)(ceng))的熔巖(yan)(yan)是(shi)由(you)兩輝(hui)安山(shan)巖(yan)(yan)構(gou)成(cheng)。巖(yan)(yan)石(shi)(shi)外觀灰色(se),普通輝(hui)石(shi)(shi)之(zhi)(zhi)(zhi)斑(ban)(ban)晶(jing)雖粗大易見(jian)但甚稀(xi)少(shao),細(xi)長之(zhi)(zhi)(zhi)紫蘇輝(hui)石(shi)(shi)晶(jing)體(ti)頗多(duo)(duo)但均細(xi)小。本巖(yan)(yan)石(shi)(shi)之(zhi)(zhi)(zhi)石(shi)(shi)基占量較多(duo)(duo),由(you)斜長石(shi)(shi)和紫蘇輝(hui)石(shi)(shi)細(xi)晶(jing)以及火山(shan)玻璃所組成(cheng)。本層(ceng)(ceng)是(shi)觀音(yin)山(shan)中(zhong)露(lu)出面積最廣的熔巖(yan)(yan),主要分布于(yu)觀音(yin)山(shan)主峰北側(ce)之(zhi)(zhi)(zhi)山(shan)坡。
第(di)(di)(di)二層斑(ban)晶(jing)(jing)稀疏之(zhi)(zhi)(zhi)(zhi)兩輝安(an)(an)(an)(an)(an)(an)山(shan)巖(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan),常(chang)含第(di)(di)(di)一層輝石(shi)(shi)斑(ban)晶(jing)(jing)多而(er)聚(ju)集成(cheng)叢的(de)普通輝石(shi)(shi)安(an)(an)(an)(an)(an)(an)山(shan)巖(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)之(zhi)(zhi)(zhi)(zhi)捕獲(huo)巖(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)塊,根據年(nian)代對比的(de)包(bao)裹定律,即可知其(qi)發(fa)生(sheng)之(zhi)(zhi)(zhi)(zhi)先后順(shun)序,乃輝石(shi)(shi)安(an)(an)(an)(an)(an)(an)山(shan)巖(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)(第(di)(di)(di)一層)早(zao)于兩輝安(an)(an)(an)(an)(an)(an)山(shan)巖(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)(第(di)(di)(di)二層)。頂層(第(di)(di)(di)三(san)層)紫蘇(su)(su)輝石(shi)(shi)安(an)(an)(an)(an)(an)(an)山(shan)巖(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)與(yu)(yu)一部(bu)分(fen)角閃石(shi)(shi)紫蘇(su)(su)安(an)(an)(an)(an)(an)(an)山(shan)巖(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)為(wei)其(qi)特征(zheng),顏色淡灰色或(huo)灰紫,斑(ban)晶(jing)(jing)細小(xiao)不(bu)顯著。有(you)時可見(jian)有(you)細長之(zhi)(zhi)(zhi)(zhi)紫蘇(su)(su)輝石(shi)(shi)或(huo)角閃石(shi)(shi)之(zhi)(zhi)(zhi)(zhi)小(xiao)晶(jing)(jing),石(shi)(shi)基較多包(bao)含微(wei)晶(jing)(jing)與(yu)(yu)玻璃質(zhi)。本層主要分(fen)布在火(huo)(huo)山(shan)中央之(zhi)(zhi)(zhi)(zhi)頂部(bu),由觀音(yin)(yin)山(shan)主峰至(zhi)崩(beng)山(shan)一帶。在本地區內除上(shang)述之(zhi)(zhi)(zhi)(zhi)三(san)層熔巖(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)流(liu)之(zhi)(zhi)(zhi)(zhi)外,還(huan)有(you)兩處獨立之(zhi)(zhi)(zhi)(zhi)小(xiao)規模火(huo)(huo)山(shan)巖(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)體(ti),一是(shi)(shi)在觀音(yin)(yin)山(shan)站北側公(gong)路旁出(chu)露之(zhi)(zhi)(zhi)(zhi)黑云母角閃安(an)(an)(an)(an)(an)(an)山(shan)巖(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)脈,為(wei)一厚約20~40公(gong)尺之(zhi)(zhi)(zhi)(zhi)脈狀小(xiao)侵(qin)入體(ti)(或(huo)稱觀音(yin)(yin)坑巖(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)脈),穿入觀音(yin)(yin)山(shan)層之(zhi)(zhi)(zhi)(zhi)粉砂(sha)巖(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)之(zhi)(zhi)(zhi)(zhi)中。另一處是(shi)(shi)突出(chu)于成(cheng)子寮附近低(di)地上(shang)之(zhi)(zhi)(zhi)(zhi)萬年(nian)塔小(xiao)山(shan),巖(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)石(shi)(shi)是(shi)(shi)橄(gan)欖石(shi)(shi)玄武(wu)巖(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan),可能是(shi)(shi)一火(huo)(huo)山(shan)側噴發(fa)之(zhi)(zhi)(zhi)(zhi)巖(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)體(ti)。萬年(nian)塔所(suo)產出(chu)者,其(qi)橄(gan)欖石(shi)(shi)含量較普通輝石(shi)(shi)為(wei)多,與(yu)(yu)福隆山(shan)玄武(wu)巖(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)略有(you)不(bu)同。根據結(jie)晶(jing)(jing)分(fen)化的(de)效應,玄武(wu)質(zhi)巖(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)漿(jiang)經由橄(gan)欖石(shi)(shi)、輝石(shi)(shi)與(yu)(yu)斜長石(shi)(shi)的(de)結(jie)晶(jing)(jing)分(fen)化可以(yi)產生(sheng)安(an)(an)(an)(an)(an)(an)山(shan)巖(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)。同樣的(de)由混(hun)染(ran)作用,也就是(shi)(shi)由基性的(de)巖(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)漿(jiang)與(yu)(yu)酸性的(de)巖(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)漿(jiang)混(hun)合,或(huo)是(shi)(shi)由玄武(wu)質(zhi)巖(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)漿(jiang),混(hun)雜了沈積物或(huo)地殼(ke)物質(zhi)都可能衍生(sheng)成(cheng)安(an)(an)(an)(an)(an)(an)山(shan)巖(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)。在觀音(yin)(yin)山(shan)地區安(an)(an)(an)(an)(an)(an)山(shan)巖(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)或(huo)玄武(wu)巖(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)中,常(chang)含有(you)火(huo)(huo)山(shan)體(ti)基底的(de)砂(sha)巖(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)或(huo)硅(gui)質(zhi)片巖(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan),顯示地殼(ke)物質(zhi)的(de)混(hun)染(ran)作用具有(you)舉足輕重的(de)角色。
觀(guan)音(yin)山(shan)(shan)各火(huo)(huo)山(shan)(shan)體(ti)的噴(pen)發時代,根據鉀-氬法定年(nian)的結果來(lai)看,觀(guan)音(yin)山(shan)(shan)火(huo)(huo)山(shan)(shan)之活動盛(sheng)行于第(di)(di)四紀。由六十余(yu)(yu)(yu)萬(wan)年(nian)前開(kai)始;接著是五(wu)十余(yu)(yu)(yu)萬(wan)年(nian)前底層輝(hui)(hui)石玄(xuan)(xuan)武(wu)巖(yan)或玄(xuan)(xuan)武(wu)巖(yan)質熔巖(yan)之噴(pen)發;其(qi)次(ci)則為四十余(yu)(yu)(yu)萬(wan)年(nian)前,第(di)(di)二(er)層兩輝(hui)(hui)安(an)山(shan)(shan)巖(yan);再依次(ci)為三十余(yu)(yu)(yu)萬(wan)年(nian)前第(di)(di)三層紫(zi)蘇(su)輝(hui)(hui)石與(yu)紫(zi)蘇(su)輝(hui)(hui)石角閃安(an)山(shan)(shan)巖(yan)之噴(pen)發;最(zui)后以(yi)二(er)十余(yu)(yu)(yu)萬(wan)年(nian)前橄欖(lan)玄(xuan)(xuan)武(wu)巖(yan)落(luo)幕(mu)。由火(huo)(huo)山(shan)(shan)噴(pen)發年(nian)代與(yu)塌陷破(po)火(huo)(huo)山(shan)(shan)口地貌(mao)看來(lai),觀(guan)音(yin)山(shan)(shan)非為活火(huo)(huo)山(shan)(shan),有可能是座休(xiu)眠火(huo)(huo)山(shan)(shan)或死火(huo)(huo)山(shan)(shan)。
1937年12月27日(ri)成立大屯公(gong)園,觀音山(shan)(shan)亦(yi)在其(qi)中。但戰后(hou)成立的(de)陽明(ming)山(shan)(shan)公(gong)園剔除觀音山(shan)(shan)(2002年方(fang)另(ling)成立北海岸及(ji)觀音山(shan)(shan)風景區管理),以及(ji)民間(jian)認(ren)為(wei)此山(shan)(shan)為(wei)風水寶地,埋下(xia)日(ri)后(hou)濫墾濫葬及(ji)水土保持(chi)的(de)問題。據(ju)估計目前山(shan)(shan)上非法墓計4萬處(chu),成為(wei)發展阻(zu)礙(ai)。