why rudra called as shiva

lord rudra halted the speed of heavenly river ganga,  when ganga was told that lord rudra will hold your speed she the ganga proudly thought that she would drown even lord rudra with her force and speed, but to her surprise when she entered the jata (hair scalp of rudra deva) she lost her self and was trapped in Rudra deva's jata.It was  like a small child entering a biggest forest. The beauty of rudra deva's jata made Ganga to feel like staying there only and keep seeing the beauty of the jata.
when Rudra deva had Ganga the purified river which was born at lord narayana's feet, which was purified with the touch of the holy feet of lord narayana, rudra deva was named shiva.shiva means pure, although lord rudra deva was pure with the knowledge still he became further pure by having Holy Ganga on his head, later again by the request of bhageeratha ganga was sent to earth.
नरसिंहाचार्य सुळिभावि
मठाधिकारि,
गुंटूर, उत्तरादिमठम्
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नरसिंहाचार्य सुळिभावि
मठाधिकारि,
गुंटूर, उत्तरादिमठम्
MOB-9493924608 ; 9490312275 visit my blog: HTTP://narasimhacharyasulibhavi.blogspot.com
to join my sms channel send sms as [ON] space [NARASIMHACHARYASULIBHAVI] to mobile number 9870807070
or http://labs.google.co.in/smschannels/subscribe/narasimhacharyasulibhavi go to this link online
you can see my prashnottara on uttaradimatham's official website uttaradimath.org in the category adhyatma jignyasa