beam roof structure dates back to the 14th century. In the churchyard may be found the graves of the Methodist Martyr William Seward, 'lawyer, author and yachtsman' Martin Beales, and Kitty (Katherine Mary) Armstrong (née Friend), victim of the notorious Hay Poisoner, a Commonwealth war grave of a Herefordshire Regiment soldier of World War I, as well as a ring of ancient yew trees. Cusop Dingle Cusop Dingle is a wooded valley near the village. It is notable in entomological history as the place where the fly Platypeza hirticeps was discovered in 1899. In the Dingle is a single track road, locally known as 'Millionaire's Row', because of the large, Victorian houses which line the route up to Offa's Dyke Path, one of the popular walking tracks in the West of England. It runs alongside the Dulas Brook (forming the border between Wales and England) into the foothills of the Black Mountains. With a multitude of waterfalls, the Dulas Brook is home to trout, otter and kingfishers. Cusop Dingle was home to the poisoner Herbert Rowse Armstrong, the only English solicitor ever hanged for murder, and the grave of his wife Katharine is in the parish churchyard. His former home, originally Mayfield but now The Mantles, was owned by Martin Beales, a solicitor working in Armstrong's old office in Hay. Beales believed that Armstrong was innocent and published a book arguing his case. Geology The bedrock is Old Red Sandstone (often referred to as the 'ORS') consisting of Upper Silurian strata overlain by the Lower Devonian. In the upper reaches of Cusop is a notable geological horizon known as the Townsend Tuff Bed, which is a volcanic air-fall ash band. Today this is a marker used in the Anglo-Welsh ORS area to divide the Silurian from the Devonian. Previously the calcrete zone "often quarried for limestone" was considered as the boundary between the Silurian and Devonian. These inorganically formed calcrete limestones were formerly known as the Psammosteus Limestones but now known as the Bishops Frome Limestone. The rock sequences have been studied by many geologists in the 19th and 20th centuries. Perhaps one of the first was Roderick Murchison who travelled this way in the early 1830s in search of material for his book The Silurian System. He notes the quarrying and even an attempt to find coal in the side of Cusop Hill near 'The Criggy' circa 1800 by