臺灣(wan)省中央(yang)山(shan)脈(mo)(mo)北(bei)部(bu)(bu)最(zui)高(gao)峰(feng)(feng)(feng)(feng)。海拔3740米(mi)(mi),僅次(ci)于(yu)(yu)玉山(shan)、雪(xue)山(shan)(副峰(feng)(feng)(feng)(feng)除外)及中央(yang)山(shan)脈(mo)(mo)中段(duan)的(de)(de)(de)(de)秀姑巒山(shan)和(he)馬博拉斯山(shan),居(ju)全省第5位(wei)。以(yi)(yi)(yi)(yi)南(nan)(nan)湖(hu)(hu)(hu)大(da)(da)(da)(da)山(shan)(主(zhu)(zhu)峰(feng)(feng)(feng)(feng))為(wei)核山(shan),周鄰約(yue)(yue)3公里(li)半(ban)徑內,3500米(mi)(mi)以(yi)(yi)(yi)(yi)上高(gao)峰(feng)(feng)(feng)(feng)共有(you)7座,皆以(yi)(yi)(yi)(yi)南(nan)(nan)湖(hu)(hu)(hu)為(wei)名(ming)(ming),簡(jian)稱北(bei)山(shan)(3535米(mi)(mi))、北(bei)峰(feng)(feng)(feng)(feng)(3580米(mi)(mi))、東(dong)(dong)峰(feng)(feng)(feng)(feng)(3639米(mi)(mi))、東(dong)(dong)南(nan)(nan)峰(feng)(feng)(feng)(feng)(3526米(mi)(mi))、中南(nan)(nan)峰(feng)(feng)(feng)(feng)(3500米(mi)(mi))、南(nan)(nan)山(shan)(3516米(mi)(mi)),為(wei)西(xi)(xi)注臺灣(wan)海峽(xia)的(de)(de)(de)(de)大(da)(da)(da)(da)甲溪(xi)和(he)東(dong)(dong)入太平(ping)洋的(de)(de)(de)(de)立霧(wu)溪(xi)分水嶺。山(shan)匯諸峰(feng)(feng)(feng)(feng)皆以(yi)(yi)(yi)(yi)粘板巖為(wei)主(zhu)(zhu)。因高(gao)度(du)(du)、位(wei)置(zhi)和(he)地勢適(shi)宜(yi),曾(ceng)是更新世冰(bing)(bing)(bing)(bing)川分布區,以(yi)(yi)(yi)(yi)主(zhu)(zhu)峰(feng)(feng)(feng)(feng)及其外圍的(de)(de)(de)(de)北(bei)、東(dong)(dong)北(bei)、東(dong)(dong)3峰(feng)(feng)(feng)(feng)為(wei)主(zhu)(zhu),遺(yi)跡保存甚(shen)多,冰(bing)(bing)(bing)(bing)蝕地形(xing)典(dian)型,有(you)冰(bing)(bing)(bing)(bing)斗冰(bing)(bing)(bing)(bing)川及山(shan)谷冰(bing)(bing)(bing)(bing)川,前者尤多。中央(yang)凹(ao)地(亦稱南(nan)(nan)湖(hu)(hu)(hu)谷地)的(de)(de)(de)(de)冰(bing)(bing)(bing)(bing)斗遺(yi)跡保存最(zui)好。南(nan)(nan)湖(hu)(hu)(hu)大(da)(da)(da)(da)山(shan)一(yi)帶,冬春季節因受(shou)來自太平(ping)洋通過宜(yi)蘭三角(jiao)洲平(ping)原(yuan)上空深入的(de)(de)(de)(de)東(dong)(dong)北(bei)風,并受(shou)大(da)(da)(da)(da)陸冷(leng)氣(qi)團東(dong)(dong)南(nan)(nan)移影(ying)響,3000米(mi)(mi)以(yi)(yi)(yi)(yi)上地區常有(you)短期(qi)積雪(xue)甚(shen)厚,由(you)此亦可(ke)推知本區昔時冰(bing)(bing)(bing)(bing)川生成和(he)冰(bing)(bing)(bing)(bing)蝕地形(xing)發育情況。據調查研究,在(zai)(zai)南(nan)(nan)湖(hu)(hu)(hu)主(zhu)(zhu)峰(feng)(feng)(feng)(feng)及其東(dong)(dong)北(bei)外圍,共已發現冰(bing)(bing)(bing)(bing)斗地形(xing)不下12處,底高(gao)在(zai)(zai)3300米(mi)(mi)以(yi)(yi)(yi)(yi)上,尤以(yi)(yi)(yi)(yi)3500米(mi)(mi)左右為(wei)多。位(wei)于(yu)(yu)主(zhu)(zhu)峰(feng)(feng)(feng)(feng)東(dong)(dong)北(bei)坡(po)的(de)(de)(de)(de)一(yi)處,徑長達(da)2500米(mi)(mi),寬約(yue)(yue)1000米(mi)(mi),其西(xi)(xi)壁中部(bu)(bu)高(gao)約(yue)(yue)1000米(mi)(mi)的(de)(de)(de)(de)陡崖,角(jiao)度(du)(du)大(da)(da)(da)(da)致60°~70°。在(zai)(zai)此西(xi)(xi)鄰,更有(you)長達(da)4000米(mi)(mi),寬約(yue)(yue)1500米(mi)(mi)的(de)(de)(de)(de)一(yi)處。估計南(nan)(nan)湖(hu)(hu)(hu)大(da)(da)(da)(da)山(shan)冰(bing)(bing)(bing)(bing)斗群形(xing)成時,雪(xue)線高(gao)度(du)(du)大(da)(da)(da)(da)致相(xiang)當3400~3500米(mi)(mi)。發源于(yu)(yu)南(nan)(nan)湖(hu)(hu)(hu)大(da)(da)(da)(da)山(shan)西(xi)(xi)側的(de)(de)(de)(de)南(nan)(nan)湖(hu)(hu)(hu)溪(xi)及與(yu)其西(xi)(xi)鄰源于(yu)(yu)雪(xue)山(shan)東(dong)(dong)北(bei)坡(po)的(de)(de)(de)(de)七家灣(wan)溪(xi)等(均大(da)(da)(da)(da)甲溪(xi)上源),均以(yi)(yi)(yi)(yi)產一(yi)種可(ke)能為(wei)冰(bing)(bing)(bing)(bing)期(qi)殘留的(de)(de)(de)(de)鮭鱒魚(yu)類著(zhu)名(ming)(ming),這(zhe)種陸封型魚(yu)類即(ji)與(yu)冰(bing)(bing)(bing)(bing)川時期(qi)低溫氣(qi)候有(you)密切聯系。