Would Google Remove Pages for Inactivity?

[OfficeFurn]

Hi,

I've been watching the Total Indexed number for 4 domains that I work with for the last few months. In Google Webmaster Tools three of them were holding steady up until August-September, when suddenly they started declining by hundreds of thousands of URLs a week.

I've asked my IT department and they say they haven't done anything technically different in the last few months that would affect indexation. I've also searched on google and on search marketing blogs to see if anyone else has experience this to no avail.

As you can see in the image, the "Not Selected" pages have not increased so it appears this is not due to duplicate content (of which we have a lot). However, the "Ever Crawled" number is increasing.

The only reasonable answer that I can conclude is that Google is now de-indexing inactive URLs? Anyone have a better answer?

yIYDm.jpg

[EGOL]

You might not have enough linkjuice into those pages to assure constant spidering.... and as a result, Google forgets those pages between crawls.