I want to generate multiple sitemaps with respect to years like news-2013.xml and news-2012.xml and want to append all files in single sitemap i.e(sitemap.xml) Any impact on ranking or indexing with this practice i`m going to follow?Any suggestions? Please share your opinions. Thanks Jack
If your site is too large then you should get idea from About.com too, it has also placed sitemap smartly and user friendly as well as SEO friendly.