Massive portion has no spheres and...do those seemingly random, elongated pits represent soft crystals that have weathered out? If so, it's time to review bladed crystals, rules out welded tuff, unless they are lapili or softer lithic fragments but usually in a tuff they are going to be parallel to bedding.

Not at all surprised to see a pregnant sphereoid since some layers are full of blueberry jelly. Different composition, though, as Nick points out, or are we seeing a "white" phase of the spheroids in the matrix?

At least one spheroid is seen to contain concentric banding. I sure hope they zap this broken sphere with all they got. The composition of each layer is really important. Look at that dark spot in the middle! Is that a diffused iron sulfide (pyrite?) Or perhaps magnetite. Hell if I know. If I had a magnet, and I was on Mars...This sphereoid don't look like no tectite to this humble observer. I believe that eliminates devitrification (for this one sphereoid), which tends to be radial. I'm not sure that supports tectites either. Did it just roll 'round alot before it got buried by other things that rolled 'round alot? The massive unit is more interesting, in some ways, that the spheroids. There's this thing, it's called a playa... I wonder... Ever been to White Sands, New Mexico? Wonder what it would look like if you really dug down deep there and looked at it at this resolution. Cool place, almost died there once...long story...only saw surface morphology though, never got a x-section view.

Sooo many non-parallel beds.

Oh this is so cool. I can't wait to see the upper part of El Capitan!

My thoughts still (cause I've no facts to close the door) lean towards sulfates. Evaporative or hydrothermal. Maybe lithified dunes 'cause the concentric bands are consistant with concretions.

Enough Arm Waving for one day.