Halliday & Matthiessen (2014: 728):
The nominal group is the primary resource used by the grammar for packing in lexical items at high density. An example is that in Figure 10-18. Here the relationships which are expressed clausally in the spoken version (the viaducts were constructed of masonry and had numerous arches in them) are instead expressed nominally (masonry viaducts of numerous arches). The clause complex is replaced by the nominal group.
