It should be now, not now. It was put forward by British geologist Lyle, the originator of geology. Talking about the past and the present is to explain the geological process in the geological history period with the geological process that is taking place in modern times, which is also called proving the past with the present. Examples are as follows:
1. By studying the difference between modern water carrier marks and wind carrier marks, we can identify the causes of wave marks in rock strata, and then understand the formation environment of rock strata. Modern water-borne wave marks are all formed in shallow water environment, so the sedimentary environment of rock layers with wave marks is obvious.
2. By studying the sedimentary structure of the modern delta, we can analyze which of the different lithologic combinations in the strata belong to the delta sedimentary strata and which part of the delta sediments each layer belongs to.
3. By studying the consequences of modern geological disasters, such as sand liquefaction caused by earthquakes, we can study geological disasters that have occurred in geological history.
4. By studying the laws of modern volcanic eruption and lava cooling, we can study the laws of volcanic activity and magma condensation revealed by different rock structures in ancient volcanic rocks.
There are countless such examples, which are widely used in sedimentology, so some geographers put forward the concept of "comparative sedimentology", which actually uses the idea of "discussing the past from the present"
You are right. Many phenomena seen in modern times are fragments of a long geological process, and human beings observe and understand nature through peeping.