What a geologist can see in the layered deposits at the delta scarp

Norbert Brügge, Germnany
Dipl.Geol.

It is sure that we do not see any fluviatile layers in the delta scarp, and certainly not sandstones. This are layers of ash and were not formed in the delta itself. The pri,ary stratification documents periodic volcanic ash rains. Such rains of differently sized ash particles have consequently also produced differently structured deposits.They occur in huge blocks in the delta  -- which is actually the moraine of a former dry ice glacier -- and were transported to this location from outside the Jezero crater. The cracks and gaps in the blocks or tilted slabs are a good indication of such transports.

Two interesting details:


Example for more solidified cyclically deposited volcanic ash.

 
This strange structure in the ash layers can be easily interpreted:

..It is probably a primary depression in the lower ash layers. A conglomerate-like volcanic boulder has knock through the lower pack and filled in the resulting cavity.Today only a remnant has been preserved in the cavity. This cavern with the filling in it must have been created before the overlying layers of ash were deposited.
A close-up of the block (right) shows that it is coarse ash filled with the volcanic bullets that are already known.

It will be continued