As mentioned before, each trail is laid by a Hare or several Hares. This is usually in advance of the trail, but sometimes it can be a 'live' Hare who sets off with a large bag of dust ahead of the main hash.
DH4 Hares typically use normal baking flour to mark the trail because it is environmentally friendly and biodegrades easily (or is eaten by wildlife, hopefully not before the trail (yes, this really does happen)). The markings are usually placed on the ground, and mostly next to an object such as a fence post, style, or lamppost etc. See the information below for common markings used on DH4 trails, which will always be explained by the Hare at the start of the trail. NB; different hash kennels use different markings - you have been warned!.
Nonetheless, the Hash House Harriers are not known by all, and we are sometimes involved in 'incidents' surrounding fear and suspicion of said markings. Social media is great for some things, not so much for other things. Ask about the tale of the incident that got escalated through the ranks to a senior Police officer, who was an ex-hasher, and was able to explain to his subordinates!