In designing the shield — the central element in what is formally called the heraldic achievement — a bishop has an opportunity to depict symbolically various aspects of his own life and heritage and to highlight particular aspects of Catholic faith and devotion that are important to him. Every coat of arms also includes external elements that identify the rank of the bearer. The formal description of a coat of arms, known as the blazon, uses a technical language, derived from medieval French and English terms, which allows the appearance and position of each element in the achievement to be recorded precisely. A diocesan bishop shows his commitment to the flock he shepherds by combining his personal coat of arms with that of the diocese in a technique known as impaling. The shield is divided in half along the central vertical line. The arms of the diocese appear on the dexter side — that is, on the side of the shield to the viewer’s left, which would cover the right side (in Latin, dextera) of the person carrying the shield. The arms of the bishop are on the sinister side — the bearer’s left, the viewer’s right.

The coat of arms of the Diocese of Rapid City, on the dexter side, shows three black triangular peaks, called piles, meant to represent the Black Hills of South Dakota. They are depicted with shamrocks at their peaks, to allude to Saint Patrick, the patron saint of the church in Lead, which served as the first cathedral of the diocese from 1902 to 1930. The background of the shield is painted gold as a reminder of the gold ore which once drew many prospectors and settlers to the region. The green (vert) region at the base of the shield recalls the rich ranch land on which many South Dakotans past and present have relied for their livelihood; it is charged with a gold circle reminiscent of the sacred circle of the Lakota people and their belief in the interconnectedness of all created things. The white wavy stripe alludes to the Missouri River, the eastern boundary of the diocese.

On the sinister side (the left side for the bearer of the shield), Bishop Bullock has chosen three symbols that represent the Holy Spirit, the Holy Scriptures/the Word, and the Blessed Virgin Mary. Behind the symbols, the shield is blue, symbolic of Our Lady. At the top of these three symbols is a white dove, surmounting a halo of golden rays, a representation of the Holy Spirit, “the Lord and giver of life,” who is the power of God by which the “Word became flesh” (Jn 1:14). Across the middle of the shield is a horizontal gold bar, called a “fess.” On the fess is an open book with parchment-colored pages, bound in a mulberry cover. The book represents the inspired Holy Scriptures, the Word of God, the very center of a bishop’s teaching ministry. At the same time, the book also suggests the written word in a more general sense, alluding to bishop’s love of literature, which he taught at the college level. Below the fess is a letter “M” in gold, symbolic of Mary upon whom the Holy Spirit descended and by whom, by Mary’s consent, the “Word became flesh.” This Marian symbol was borrowed from the shield of Saint John Paul II, a lifetime hero of the bishop and who was the reigning pope when bishop was ordained a deacon and a priest. Altogether, the three symbols speak of God’s life and salvation, bestowed by the descent of the Holy Spirit, coming in the Word and through the humanity given by the Mother of God, in Jesus Christ. That saving humanity is offered each time we gather at the source and summit of the Christian life, the Eucharist, where the Word becomes flesh for our salvation.