 Ramba uchinyora ndima iyi - Nhoroondo yokuumbwa kweMakomo eCascade inodzokera shure kumamiriyoni emakore akapfuura kusvika kumagumo eEocene Epoch. Zviitiko zvegadziriro yenyika zvakaitika makore mazhinji akapfuura zvakagadzira nzvimbo dzakasiyana-siyana uye kuchinja kwakanyanya kwepamusoro pamusoro peCascade Range kunotungamirira kumusiyano wemamiriro okunze akasiyana-siyana. Mukati mePleistocene nguva inodzokera shure makore anopfuura mamiriyoni maviri apfuura, kuvira kwechando kunopfuurira uye kudzokera shure kwakatsvaira nokuumba nzvimbo yacho. NePlate yokuNorth America ichipfuura Plate yokuPacific, zviitiko zvebasa remakomo anoputika zvakaitika. Kuputika kweGomo reSt. Helens kwakaitika muna 1980rakanga rakanangidzirwa kuMinnie Peak ndokubvisa zvinomera mumateru aro. Nemhaka yokuva pedyo kweGomo reSt. Helens neMinnie Peak, madota anoputika anowanzoitika munharaunda yacho. Gomo reMinnie Peak neGomo reWhittier riri pedyo rakagadzirwa ne granodiorite yakasimba yeLake Spirit pluton, inova ibwe rakaoma-rakanyungudutswa rakapinda mumatombo akapoteredza makore anenge mamiriyoni 20 akapfuura. 