Should we block URL param in Webmaster tools after URL migration?

[eCommerceSEO]

Hi,

We have just released a new version of our website that now has a human readable nice URL's. Our old ugly URL's are still accessible and cannot be blocked/redirected. These old URL's use a URL param that has an xpath like expression language to define the location in our catalog.

We have about 2 million pages indexed with this old URL param in it while we have approximately 70k nice URL's after the migration. This high number of old URL's is due to facetting that was done using this URL param.

I wonder if we should now completely block this URL param from Google Webmaster tools so that these ugly URL's will be removed from the Google index. Or will this harm our position in Google?

Thanks,

Chris

[gmk1567]

You said as the old URLs can not be redirected.

Then why don't you try for canonical implementation in the important pages to avoid losing link authority that  might have built over the years naturally.

The rest of the URLs can be blocked through GWT using parameters. Since you have new version of site, you may want to concentrate only on the new pages. If the old pages are not redirected, anyway you are going to be benefited.

I would suggest to go with canonical wherever possible and URL parameters only as a last option.

Note: To have canonical, pages need to have more similarities