You must now invoke the Detailed Surface Scanner, and witness the beautiful blue overlay that will appear once you map the planet. It will guide you. Be sure to press the filter keys if there are more than one type. Then you fly down to where it's blue, and get really low and slow, and look for them. Or get out and drive around in the SRV looking.
So I hope you have good eyesight, and a lot of patience. That's how it works now.