峨山屬高原地貌形態(tài),地形東部狹長,西部較寬。境內(nèi)海拔2000以上的高山有60多座,較大的有高魯山、大西山、總果山、大黑山、火石頭山等。地勢東北高、西南低。東部因受曲江(縣境稱猊江)切割,形成西北至東南走向的山地與谷地相間的地貌形態(tài)。中部的岔河、塔甸、富良棚等鄉(xiāng)屬巖溶比較發(fā)育的石灰?guī)r地區(qū),群山起伏,溶洞、洼地較多,有地下溝、河分布,地面水源較缺。西部和北部,山高坡陡,箐深谷狹,地形破碎。全縣平均海拔1691米,最高點(diǎn)為北部甸中鎮(zhèn)鏡湖行政村的火石頭山,海拔2583.7米,最低點(diǎn)在西部綠汁江邊的丫勒,海拔820米。峨山地層出露比較齊全,從最新的第四系到古到老的昆陽群地層均有出露,而以距今7000萬年至2.25億年的中生界地層分布最廣,約占全縣總面積的60%以上。峨山地處康滇地盾東界,燕山運(yùn)動(dòng)時(shí)期(距今7000萬年左右),康滇地盾發(fā)生強(qiáng)烈褶皺、形成了許多斷裂帶,縣境東部的雙江、小街等地,位于曲江斷裂帶上,地殼運(yùn)動(dòng)劇烈,地震活動(dòng)頻繁。據(jù)史料記載,從清康熙三十五年(1695年)至公元1970年的275年間,曾發(fā)生過7次較大地震。發(fā)生于1970年1月5日凌晨1時(shí)零分34秒的一次大地震,震級(jí)達(dá)里氏7.7級(jí),震中在小街鎮(zhèn)大海洽行政村駐地梅子樹村。這次地震波及云南省南部的大部地區(qū),以峨山、通海、華寧、建水等縣災(zāi)情最重。峨山受災(zāi)面積達(dá)475.8平方公里,占全縣總面積的23.58%。小街、雙江等鎮(zhèn)的人民生命財(cái)產(chǎn)遭受嚴(yán)重?fù)p失。
Geographical survey of Eshan
Eshan,which belongs to plateau landform, with a long topography in east and more widen in west. In Eshan, there are more than 60 mountains with a height of 2000 meters above sea-level, just as Gaolushan, Daxishan, Zongguoshan, Daheishan, firestone hill etc. The ground falls away from northeast to southwest. Because of the Qu river (it is also called Xu river), it weathered out into long northwest to southeast, and also with an alternation landform of mountain and valley. In the middle part, just like Chahe, Tadian, and fuliangpeng, are belong to limestone area, where with mountain, limestone hole and depression in it. Although there are channels or rivulets, it lacks water resources supply. In the west and north part, the mountain rise up in a steep, and with long with-drawing vale and fragmentation platform. Eshan lies at an average of 1691 meters above sea-level, The highest point is firestone hill, Jinghu administrative village, Dianzhong town in north part, It rises to a height of over 2583.7 meters above sea-level. Contrarily, the The lowest point is Yale, which lies by Luzhi river in west part, and with a height of 820 meters above sea-level. The portion of stratum in Eshan is of stratigraphic cob, and the part of a rock formation that appears above the surface are from the latest fourth series to ancient Kunming stratum. It contains the Mesozoic Erathem stratum which is from 70 million to 225 million years ago spread widely, and occupied 60% of total area. Eshan situated in the east of Yunnan, and a violent earthquake occurred there and formed many rifts during yanshan hill crustal movement(70 million years ago). Because the Shuangjiang, Xiaojie etc.in Eshan county lies on rifts, earthquakes occurred frequently. According to historical records, there had happened 7 earthquakes between 275 yeas, from the reign of Kang Xi(1695) to 1970 a.d.. The worst one happened at plum tree village, Xiaojie town on 1:0'34"at dawn,January5, 1970, magnitude reached 7.7. The earthquake affected most of Yunnan, especially in Eshan, tonghai,huanning jianshui and around, and 475.8 square kilometers were affected in Eshan, it occupied 23.58% of the total area. The losses in Xiaojie, shuangjiang etc. caused by the disaster were serious.