Dear Authors,

I have been in close contact with both reviewers. Both reviewers have reinforced their opinion to me that
(1) the error analysis must be integrated into the paper and not included in the supplementary material. This should be possible.
(2) the English must be dramatically improved to consider final publication. Please take the comments of reviewer 1 seriously.

Here is an example of how I believe the abstract should be rewritten:
Gravel cushions are widely used to absorb the impact energy of falling rocks in open-pit mines. A particularly important application is on enhance the energy absorbing capacity of rockfall sheds. In this paper we study how cushion layers of different thickness and particle size influence the energy consumption and buffer mechanisms of gravel cushions. We performed a series of laboratory drop tests by dropping blocks from varying heights on different cushion materials. The results indicate that for a given impact energy, the change of cushion’s thickness has a strong influence on the measured coefficient of restitution (COR) and therefore impact pressure. Additional tests were performed to study how block radius affects the measured COR. Blocks with a large radius exhibit a larger variability in measured COR. Finally we investigated the influence of particle size. The test results reveal that the cushion’s thickness h is the primary design parameter, controlling not only COR but also stability of the cushion material. The results provide a theoretical and practical basis for the design of gravel cushions for rockfall protection.

I expect the entire paper to be greatly improved.

I therefore believe publication is warranted after major revisions. I believe the paper should be submitted as a brief communication. Try to shorten the paper and concentrate on the tests and the results. There is no need to have a long introduction to motivate the problem and laboratory tests. I will not allow the paper to be published unless there are significant improvements to the written English.
Let me underscore my opinion that the dynamic tests of cushion material for rockfall sheds is an important and practical topic, very relevant for NHESS. The data must be presented in a way that the results are assessable to other researchers working in this field.

Dear Authors,

Both reviewers are satisfied with the revisions; however, they still believe that the paper can be improved, especially by improving the graphics, english and presentation of the equations. Please see the report of reviewers 1 and 2 who both make helpful suggestions for improvement of the final manuscript.

Many thanks for your revised manuscript. I think it is now ready for publication.