The first pic looks like modified bitumen membrane, the second looks like exposed asphalt built up. UV does deteriorate exposed asphalt, but it is an accepted roofing practice. It just needs to be recoated every 5 years. When stone ballast is embedded in the flood coat, it not only contributes to wind uplift resistance, but protects the flood coat from UV.
Jim King
The Ads are the main reason I subscribe.
New products come into the market place…I get further info and installation manuals/instructions from the Ad weblinks…when I run across material I’ve never seen before except in print…I’m ahead of the game and don’t look like an idiot when standing on 100,000 sq.ft roof with a client asking, “What is this material?” and not having any clue (not that this has ever happened)…ego and lack of knowledge are extremely hard to swallow in these situations…especially at my fees
HTH
These pictures is of a EPDM roof.
And this is of a Modified Bituminous roof Membrane.
Membrane degradation due to exposure to chemicals, oils and UV is a concern with modified bitumen.
Known Issues
Alligatoring
Cracking of a membrane roof producing a pattern similar to an alligator’s hide. Granule loss accelerats this condition unless the membrane is protected by a roof coating.
Seam Failure
Open and unadhered seams are often the caused by improper torch application. They must be repaired immediately while the membrane is still in good condition.
Ponding Water
Retention of water on a caused by inadequate roof drainage or structural deflection. Water can enter failed seams or punctures and cause leaks.
Modified Bitumen Roof Maintenance
Leaks in modified bitumen roofs are difficult to isolate and a seamless roof coating system is a cost effective solution.
The surfacing of the sheets is also a maintenance concern. Modified Bitumen sheets are not as sensitive to ultraviolet light as built up roofs but there is still degradation. Studies have indicated that a reflective coating applied within five years of installation can extend the service life of the membrane by 10 or more years.
Water-borne or solvent-borne roof coatings may be used. However, a solvent-based coating offers greater resistance to ponding water.
Marcel 
The modified bitumen I see always has granules for uv.
If not , it would need silvering.
I think gravel roof days are over for the most part aren’t they?
Hard to tell from the photo, but looks like toarch down to me. If it is, you would not put down gravel. It is recommended that a sealer be applied every few years to help extend the life of the material.
If it is a hot mop (tar paper & hot ashpalt) then yes, at least where I come from.